South Georgia State College
Quantway™ I
Module 1
Student
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This Module is part of QUANTWAY™, A Pathway Through College-Level Quantitative Reasoning, which is a product of a Carnegie Networked Improvement Community that seeks to advance student success. The original version of this work, version 1.0, was created by The Charles A. Dana Center at The University of Texas at Austin under sponsorship of the Carnegie Foundation for the Advancement of Teaching. This version and all subsequent versions, result from the continuous improvement efforts of the Carnegie Networked Improvement Community. The network brings together community college faculty and staff, designers, researchers and developers. It is a research and development community that seeks to harvest the wisdom of its diverse participants through systematic and disciplined inquiry to improve developmental mathematics instruction. For more information on the QuantwayTM Networked Improvement Community, please visit .
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Quantway™ is a trademark of the Carnegie Foundation for the Advancement of Teaching. It may be retained on any identical copies of this Work to indicate its origin. If you make any changes in the Work, as permitted under the license [CC BY NC], you must remove the service mark, while retaining the acknowledgment of origin and authorship. Any use of Carnegie’s trademarks or service marks other than on identical copies of this Work requires the prior written consent of the Carnegie Foundation.
This work is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported License. (CC BY-NC)
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Table of Contents
Module 1
E-Understanding Visual Displays of Information 5
G-Writing About Quantitative Information 6
|Lesson |Title |Theme |Page |
|1.1 |Introduction to Quantitative Reasoning |Citizenship | |
| | Student Handout | |7 |
| | Out-of-Class Experience | |11 |
|1.2 |Seven Billion and Counting |Citizenship | |
| | Student Handout | |22 |
| | Out-of-Class Experience | |28 |
|1.3 |Percentages in Many Forms |Personal Finance | |
| | Student Handout | |36 |
| | Out-of-Class Experience | |41 |
|1.4 |The Flexible Quantitative Thinker |Personal Finance | |
| | Student Handout | |51 |
| | Out-of-Class Experience | |56 |
|1.5 |The Credit Crunch |Personal Finance | |
| | Student Handout | |67 |
| | Out-of-Class Experience | |73 |
|1.6 |Whose Footprint Is Bigger? |Citizenship | |
| | Student Handout | |81 |
| | Out-of-Class Experience | |87 |
|1.7 |A Taxing Set of Problems |Personal Finance | |
| | Student Handout | |93 |
| | Out-of-Class Experience | |98 |
|1.8 |Interpreting Statements About Percentages |Medical Literacy | |
| | Student Handout | |105 |
| | Out-of-Class Experience | |110 |
|1.9 |Percents and Probabilities |Medical Literacy | |
| | Student Handout | |115 |
| | Out-of-Class Experience | |120 |
| |Review | |127 |
Data are increasingly presented in a variety of forms intended to interest you and invite you to think about the importance of these data and how they might affect your lives. The following are some of the types of common displays:
• pie charts,
• scatterplots,
• histograms and bar graphs,
• line graphs,
• tables, and
• pictographs.
In your lessons, you will find a variety of such collections of data.
What questions should you ask yourself when you study a visual display of information?
• What is the title of the chart or graph?
• What question is the data supposed to answer? (For example: How many males versus females exercise daily?)
• How are the columns and rows labeled? How are the vertical and horizontal axes labeled?
• Select one number or data point and ask, “What does this mean?”
Use the following chart to help you understand what some basic types of visual displays of information tell you and what questions they usually answer.
|This looks like a … |This visual display is usually used to … |For example, it can be used to show … |
|pie chart |show the relationships between different |how time is used in a 24-hour cycle. |
| |parts compared to a whole. |how money is distributed. |
| | |how something is divided up. |
|line graph |show trends over time. |what seems to be increasing. |
| |compare trends of two different items or |what is decreasing. |
| |measurements. |how the cost of gas has increased in the last |
| | |10 years. |
| | |which of these foods (milk, steak, cookies, eggs) has risen most |
| | |rapidly in price compared to the others. |
|histogram or bar graph |compare data in different categories. |how a population is broken up into different age categories. |
| |show changes over time. |how college tuition rates are changing over time. |
|table |organize data to make specific values |the inflation rates over a period of years. |
| |easy to read. |how a population is broken into males and females of different age |
| |break data up into overlapping |categories. |
| |categories. | |
Background
You might be surprised that you are asked to write short responses to questions in Quantway. Writing in a math class? This course emphasizes writing for the following two reasons:
• Writing is a learning tool. Explaining things such as the meaning of data, how you calculated the data, or how you know your answer is correct deepens your own understanding of the material.
• Communication is an important skill in quantitative literacy. Quantitative information is used widely in today’s world in products such as reports, news articles, publicity materials, advertising, and grant applications.
Understanding the Task
One important strategy in writing is to make sure you understand the task. In this course, your tasks will be questions in assignments, but in other situations the task might be a question on a report form, instructions from your employer, or a goal that you set for yourself. To begin to write successfully, ask yourself the following questions:
• What is the topic of the writing task?
• What is the task telling me to do? Some examples are given below:
o Describe how you found the answer.
o Explain why you think you have the right answer.
o Reflect on the process of coming up with the answer.
o Make a prediction about the next data point.
o Compare two data points or the answers to two parts of the problem.
• What information am I given to help me with the task?
Look at this example and the answers it gives to these questions.
|(12) In OCE 1.4, you read about self-regulating your learning during the plan phase. Explain briefly why it is important to |
|evaluate your confidence before planning on working a problem. |
• What is the topic of the writing task? (Answer: It is about self-regulating or evaluating confidence.)
• What is the task telling me to do? (Answer: It is asking me to explain why “evaluating confidence” is important.)
• What information am I given to help me with the task? (Answer: I can look back at the OCE for Lesson 1.4 if I need to remember what self-regulating is.)
A Basic Writing Principle for Quantitative Information
Writing Principle: Use specific and complete information. The reader should understand what you are trying to say even if he or she has not read the question or writing prompt. This includes
• information about context, and
• quantitative information.
Specific Objectives
Students will understand that
• quantitative reasoning is the ability to understand and use quantitative information. It is a powerful tool in making sense of the world.
• relatively simple math can help make sense of complex situations.
Students will be able to
• identify quantitative information.
• round numbers (based on homework).
• name large numbers (based on homework).
• work in groups and participate in discussion using the group norms for the class.
Problem Situation: Does This Information Make Sense?
In this lesson, you will learn how to evaluate information you see often in society. You will start with the following situation.
You are traveling down the highway and see a billboard with this message:
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(1) You do not see the name of the organization that put up the billboard. What groups might have wanted to publish this statement? What are some social issues or political ideas that this statement might support?
The information in this statement is called quantitative. Quantitative information uses concepts about quantity or number. This can be specific numbers or a pattern based on numerical relationships such as doubling.
You hear and see statements using quantitative information every day. People use these statements as evidence to convince you to do things like
• vote a certain way
• donate or give money to a cause
• understand a health risk
You often do not know whether these statements are true. You may not be able to locate the information, but you can start by asking if the statement is reasonable. This means to ask if the statements make sense. You will be asked if information is “reasonable” throughout this course.
This lesson will help you understand what is meant by this question.
(2) In 1995,[1] a group published the statement in the Problem Situation. Do you think this was a reasonable statement to make in 1995? Discuss with your group.
(3) You only have the information in the statement. Using only that information, how can you decide if the statement is reasonable? Talk with your group about different ways in which you might answer this question.
(4) In Question 3, you thought about ways to decide if the statement was reasonable. One approach is to start with a number for the first year. Put this number into the table below. Complete the other values in the second column of the table. Do not complete the third column right now.
|Year |Number of Children |Rounded (using words) |
|1950 | | |
|1960 | | |
|1970 | | |
|1980 | | |
|1990 | | |
|1995 | | |
(5) Does the number you predicted for the number of children shot in 1995 seem reasonable? What kind of information might help you decide?
Making Connections
Record the important mathematical ideas from the discussion.
About This Course
This course is called a quantitative reasoning course. This means that you will learn to use and understand quantitative information. It will be different from many other math classes you have taken. You will learn and use mathematical skills connected to situations like the one you discussed in this lesson. You will talk, read, and write about quantitative information. The lessons will focus on three themes:
• Citizenship: You will learn how to understand information about your society, government, and world that is important in many decisions you make.
• Personal Finance: You will study how to understand and use financial information and how to use it to make decisions in your life.
• Medical Literacy: You will learn how to understand information about health issues and medical treatments.
This lesson is part of the Citizenship theme. You learned about ways to decide if information is reasonable. This can help you form an opinion about an issue.
Today, the goal was to introduce you to the idea of quantitative reasoning. This will help you understand what to expect from the class. Do not worry if you did not understand all of the math concepts. You will have more time to work with these ideas throughout the course. You will learn the following things:
• You will understand and interpret quantitative information.
• You will evaluate quantitative information. Today you did this when you answered if the statement was reasonable.
You will use quantitative information to make decisions.
Student Notes
Introduction
Since this is your first assignment, the authors will be explaining how your daily assignments will be structured. An assignment is referred to as an Out-of-Class Experience (OCE). Each OCE has the same four sections:
• Making Connections to the Lesson
• Developing Skills and Understanding
• Making Connections Across the Course
• Preparing for the Next Lesson and/or Assessment
Making Connections to the Lesson
The purpose of this section is to help make sure you understand the most important ideas of the lesson. Sometimes it is hard to know what to focus on when you are in class. The authors have designed this curriculum to help you identify and remember important ideas through the following steps:
• Every lesson ends with a discussion. During this discussion, the class identifies the important mathematical ideas of the lesson.
• The Student Handout always ends with a section called Making Connections. In this section, you write down the important mathematical ideas.
• This section of your OCE always starts with a question that asks you to identify a main mathematical idea of the lesson. You are given four statements to choose from.
• In future OCEs, you will describe how mathematical ideas connect across lessons.
A main mathematical idea means that the idea is an important concept that helps explain how to do many different types of problems and helps connect different problems together. It may take you a while to be able to identify the main mathematical ideas of lessons. Your instructor will help you at first by making sure these ideas are discussed at the end of the lesson.
(1) Which of the following statements correctly illustrates one of the main mathematical ideas of the lesson?
(i) Asking good questions about quantitative information is important in quantitative reasoning.
(ii) Doubling means to multiply by 2.
(iii) Gun violence is a problem in the United States.
(iv) You should not use estimation.
Since this is your first time with this type of question, the authors are going to explain the answer to Question 1. The answer is (i) because asking questions about quantitative information is important in many different problem situations. The other answers may or may not be true, but they are not main mathematical ideas for this lesson. Specifically,
• (ii) is true, but it only applies to one type of procedure: doubling.
• (iii) is an opinion. You cannot say if it is true or false, and it is not a mathematical idea.
• (iv) is not true. As you saw in the lesson, estimation is a valuable skill.
Developing Skills and Understanding
The purpose of this section of the OCE is for you to practice with the skills and concepts from the lesson. You will see questions directly related to the lesson. You will also see questions that apply the skills and concepts to different situations. The section will sometimes have reading material that helps explain the topics from the lesson. Later in the course, you can look back at this information as you review what you have learned.
Questions 2 and 3 highlight important quantitative reasoning skills that you will learn in this course.
Quantitative Reasoning Skill: Reading and interpreting quantitative information
The lesson from class focused on a statement about children “gunned down” in America. How was such an inaccurate statement published? It was based on another statement published earlier.[2] Both statements are shown below. Read them carefully and decide what each means mathematically.
|Original Statement: The number of American children killed each year by guns has doubled since 1950. |
|Reworded Statement (circa 1995): Every year since 1950, the number of American children gunned down has doubled. |
(2) Based on the original statement and the reworded statement, which of the following comments is valid?
(i) Both the original and reworded statements are interpreted to mean that the number of children gunned down has doubled every year between 1950 and 1995.
(ii) The interpretation of the reworded statement implies that the number of children gunned down has doubled once between 1950 and 1995.
(iii) Assume that the original statement is true. If approximately 100 children were killed by guns in 1950, the number of children killed by guns in 1995 was about 200.
(iv) The phrase “children killed” has the same meaning as “children gunned down.”
This highlights the importance of reading and writing carefully about quantitative information. The original and reworded statements look very similar, but mean entirely different things:
• The original statement says that the number has doubled once from 1950 to the published date (1995).
• The reworded statement says that the number has doubled every year between 1950 and the published date (1995).
Quantitative Reasoning Skill: Identifying information that can be verified (checked to see if it is true)
(3) Which of the following statements contain quantitative information? There may be more than one correct answer.
(i) Many Americans have diabetes.
(ii) ABC News reported that the number of Americans that have diabetes could triple in the next
40 years.[3]
(iii) About a fourth of Americans with diabetes are over 65 years old according to the American Diabetes Association.[4]
(iv) Diabetes is a terrible disease.
One characteristic of quantitative information is that it contains numerical information. Another is that it has information that can be checked or evaluated. The statement “Many Americans have diabetes” sounds quantitative. Many implies a number, but it is also a judgment. How much is many? There is no way to verify this statement because you could have different opinions about the meaning of “many.” “Diabetes is a terrible disease” is also a judgment. You can offer quantitative information to support the statement, but you cannot verify that this is true or false. Being able to evaluate a claim based on quantitative information is an important quantitative reasoning skill.
Quantitative Reasoning Skill: Naming and estimating large numbers
Large numbers often occur in real-life situations, but it is hard to make sense of them. It is difficult to imagine the distinction between a million and a billion. You will do more work with understanding the size of these numbers in Lesson 1.2, but first you will work on recognizing the numbers and names. If you need some review on place value, you can view the following videos:
• video/place-value-1?playlist=Developmental%20Math
• video/place-value-2?playlist=Developmental%20Math
• video/place-value-3?playlist=Developmental%20Math
(4) The following place-value chart is partially labeled.
Place-Value Chart
|Hundred trillions | | |
|Number of children and adults with diabetes in| |25.8 million |
|2010 | | |
|Number of children under age 20 with diabetes |215,000 | |
|in 2010 | | |
|Cost due to diagnosed diabetes cases in |$174,000,000,000 | |
|2007—includes medical costs, disability | | |
|payments, loss of work, and premature death | | |
Quantitative Reasoning Skill: Rounding numbers
Another important skill you used in this lesson is rounding. You often round numbers when you are trying to make sense out of them or make comparisons and do not need exact numbers. In this lesson, you found that the statement predicted that trillions of children were gunned down in 1995. This was enough to know that the statement was not reasonable because that was more than the entire population of the United States (and in fact, the world). You did not need to have exact numbers.
If you need review on rounding, you can view the following videos:
• video/rounding-whole-numbers-1?playlist=Developmental%20Math
• video/rounding-whole-numbers-2?playlist=Developmental%20Math
• video/rounding-whole-numbers-3?playlist=Developmental%20Math
(8) The following website has two population clocks that update every minute to show the estimated populations of the United States and the world (main/www/popclock.html). At 7:29 p.m. (central standard time) on April 5, 2011, the clocks showed the following values.
| |Estimated Population Count |Rounded Number (round to the |Name of Rounded Number |
| |from Website |place value indicated) | |
|U.S. population |311,105,182 |311,000,000 |311 million |
| | |(round to nearest million) | |
|World population |6,910,152,824 |7,000,000,000 |7 billion |
| | |(round to nearest billion) | |
(a) Go to the population clock website. Record the current population estimates and the time at which you recorded them. Complete the table as indicated.
Time recorded: ________________
| |Estimated Population Count |Rounded Number (round to the |Name of Rounded Number |
| |from Website |place value indicated) | |
|U.S. population | | | |
| | |(round to nearest million) | |
|World population | | | |
| | |(round to nearest billion) | |
(b) Wait at least 10 minutes and go back to the population clock (either close and reopen the website or refresh the website). Record the new values.
Time recorded: ________________
| |Estimated Population Count |Rounded Number (round to the |Name of Rounded Number |
| |from Website |place value indicated) | |
|U.S. population | | | |
| | |(round to nearest million) | |
|World population | | | |
| | |(round to nearest billion) | |
(c) Did the estimated population counts change?
(d) Did the rounded numbers change?
(e) If you were making a calculation based on population, would you use the population count or the rounded number? Be prepared to justify your answer.
Making Connections Across the Course
This section of the OCEs will help you make connections between concepts across the course. In Making Connections, you will be using concepts, skills, and situations from previous assignments and previewing topics you will use in later assignments.
There are five lessons in the first unit of the course: 1.1–1.5. These lessons will help you develop some very important skills you will use throughout the course. These include the following:
• Reading quantitative information.
• Writing statements using quantitative information.
• Understanding large numbers:
o place value.
o reading and writing large numbers in both words and digits.
o the size of numbers.
o comparing the relative size of numbers.
• Estimation.
• Understanding, estimating, and calculating percentages.
• Fundamentals of calculations:
o order of operations.
o different ways to write and perform calculations.
By the end of this module, you should also understand some important points about this course:
• What quantitative reasoning is.
• Your responsibility for:
o creating and contributing to the classroom learning environment.
o being prepared for class.
o completing your work.
o planning and monitoring your own learning and course progress.
• How to be an effective member of a work group.
• Strategies for working on difficult problems.
The following questions will help you prepare for this course:
(9) What are your goals for this class?
(10) What academic and nonacademic strengths do you bring to the class? Examples: time to work in the tutoring center or to meet with classmates, good support at home so you can focus on your studies, confidence in yourself based on your past experiences either in school or in other aspects of your life.
(11) Do you have any questions or concerns you want to ask your instructor?
Preparing for the Next Lesson (1.2)
Your instructor expects you to be prepared for the next class. This section tells you what you need to know and be able to do to be prepared. You will be asked to rate how confident you are that you can do certain things. Be honest when you rate yourself. You will not be graded on the rating. If you do not feel confident, get help on the topic before class. Talk to your instructor about ways you can get help on campus.
Reread the information from Lesson 1.1 that describes this course:
This course is called a quantitative reasoning course. This means that you will learn to use and understand quantitative information. It will probably be different from any other math class you have ever taken. You will learn and use mathematical skills, but they will be connected to situations like the one you discussed in this lesson. You will talk, read, and write about quantitative information. The lessons will focus on three themes:
• Issues of citizenship: understanding your society, government, and world (the situation from today’s lesson is an example)
• Personal finance: understanding financial information and how to use it to make decisions
• Medical literacy: understanding the meaning of information about risk of disease and effectiveness of treatment
The purpose of today’s lesson was to introduce you to the idea of quantitative reasoning and give you
a picture of what the class will be like. Do not worry if you did not understand all of the math concepts. You will have more time to work with these ideas throughout the course. Some other skills you will
learn are
• how to understand and make sense of quantitative information.
• how to evaluate quantitative information (like you did in this lesson when you were asked if the statement was reasonable).
• how to use quantitative information to make decisions.
(12) Give one example for each theme that would be of particular interest to you (possibly an experience or a question that you have encountered).
(a) Issue of citizenship
(b) Issue of personal finance
(c) Issue of medical literacy
Self-Regulating Your Learning—An Introduction
One goal of this course is to increase your ability to learn efficiently and effectively. This means learning faster and learning smarter—what scientists call being a “self-regulated learner.” The following section explains what this means.
Self-regulating your learning means you plan your work, monitor your work and progress, and then reflect on your planning and strategies and what you could do to be more effective. These are the three phases of Self-Regulated Learning (SRL). They are introduced below, and will be followed up on later on in the course.
Plan: Before doing a problem or assignment, self-regulated learners plan. They think about what they already know or do not know, decide what strategies to use to finish the problem, and plan how much time it will take. Research has shown that math experts often spend much more time planning how they will do a problem than they do actually completing it. Novices, the people who are just starting out, often do the opposite.
Work: Self-regulated learners use effective strategies as they work to solve problems. They actively monitor what study strategies are working and make changes when they are not working. When they do not know which strategy would be better, they ask for help. Self-regulated learners also keep themselves focused while they are working and pay attention to their feelings to avoid getting frustrated.
Reflect: Usually after an assignment or problem is done, self-regulated learners take time to reflect about what worked well and what did not. Based on that reflection, they think about
how to change their approach in their future. The reflect phase helps self-regulated learners understand more about how they learn so they can become more efficient and more effective
the next time. Reflecting is important for doing a better job next time you plan for a new problem or assignment.
You can think of these three phases as a cycle. You incorporate what you learned during the reflect stage in your next plan phase, making you a more effective learner as you repeat this process many times. The most effective students get in the habit of working this way:
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For most people, self-regulating takes time, practice, and hard work, but it is always possible. People can improve even if, in the beginning, they did not self-regulate their learning very well. The more you practice something and the more you train your brain to think in certain ways, the easier it becomes.
Since thinking this way takes practice, you will have opportunities to practice some of these skills as you progress through this course. As you read through the lessons and homework assignments, you will encounter activities that are designed to help you to incorporate the Plan, Work, and Reflect phases in specific ways. Take the time to thoughtfully complete these exercises. The payoff will be worth it!
Self-Regulated Learning—Plan
Part of effectively planning for what could be new material for you is figuring out how much you already know. In Lesson 1.2, you will need to be able to do the following things:
• Double values in contextual situations.
• Identify place value to the trillions.
• Read a table of numbers.
• Add and subtract numbers.
(13) To effectively plan and use your time wisely, it helps to think about what you know and do not know. For each of the following, rate how confident you are that you can successfully do each task. Use the following descriptions to rate yourself:
5—I am extremely confident I can do this task.
4—I am somewhat confident I can do this task.
3—I am not sure how confident I am.
2—I am not very confident I can do this task.
1—I am definitely not confident I can do this task.
Before beginning Lesson 1.2, you should understand the concepts and demonstrate the skills listed below:
|Skill or Concept: I can… |Rating from 1 to 5 |
|Double values in contextual situations. | |
|Identify place value to the trillions. | |
|Read a table of numbers. | |
|Add and subtract numbers. | |
Specific Objectives
Students will understand that
1 billion = 1,000 x 1,000 x 1,000.
the representations, one billion, 1,000,000,000, and 109 have the same meaning.
population growth can be measured in terms of doubling time.
doubling times can be used to compare population growth during different periods.
Students will be able to
calculate quantities in the billions.
convert units from feet to miles.
use data to estimate a doubling time.
compare and contrast population growth via population doubling times.
Problem Situation 1: How Big Is a Billion?
Scientists have worried about human population growth for nearly 200 years. The population of Earth has grown over time and is still growing. You do not know how many people Earth can support. In this lesson, you will get a sense of how many people there are and how that number has changed over time.
The world population is estimated to be about 7 billion people. That is seven times as many people as there were 200 years ago.
It is difficult to understand just how big a billion is. Here is a way to help you think about it.
1 billion = 1,000 x 1,000 x 1,000 = 1,000,000,000 = 109
The following questions will also help you think about how big 1 billion is.
(1) Imagine a line of 1,000 people standing shoulder to shoulder. How long is the line? Complete the following steps to answer this question. For each step, write your calculations clearly so that someone else can understand your work.
(a) Estimate the shoulder width of an “average” person. Use that estimate in the following calculations. Calculate how far a line of 1,000 people, standing shoulder to shoulder, would measure in miles (5,280 feet = 1 mile). Record your answer in the table below.
(b) Imagine 1,000 lines of 1,000 people. How many people would be in line? How long is the line in measured in miles? Record your answers in the table below.
(c) Imagine 1,000 lines like the one in Part (b). How many people would be in line? How long is the line in measured in miles? Record your answers in the table below.
|Number of People |Length of Line (miles) |
|(a) 1,000 |0.3788 |
|(b) |379 |
|(c) |378,787 |
Problem Situation 2: Measuring Population Growth
In the next section, you will look at doubling times to determine how the human population of the earth has changed over time. The doubling time of a population is the amount of time it takes a population to double in size. Calculating doubling time helps you understand how fast a population is growing. Comparing doubling times helps you understand how growth is changing over time.
Example
Table 1 gives historical estimates of the human population. The population in 8,000 BCE was estimated to be 5 million people. Two-thousand years later, in 6,000 BCE, the population had doubled to 10 million people. Therefore, the population doubling time for 8,000 BCE is about 2,000 years.
Table 1
Population Estimates Throughout History[6]
|Year |World Population | |Year |World Population |
| |(Lower bound, in | | |(Lower bound, in |
| |millions) | | |millions) |
|10,000 BCE |1 | |1850 |1,262 |
|9,000 BCE |3 | |1900 |1,650 |
|8,000 BCE |5 | |1950 |2,519 |
|7,000 BCE |7 | |1955 |2,756 |
|6,000 BCE |10 | |1960 |2,982 |
|5,000 BCE |15 | |1965 |3,335 |
|4,000 BCE |20 | |1970 |3,692 |
|3,000 BCE |25 | |1975 |4,068 |
|2,000 BCE |35 | |1980 |4,435 |
|1,000 BCE |50 | |1985 |4,831 |
|500 BCE |100 | |1990 |5,263 |
|AD 1 |200 | |1995 |5,674 |
|1000 |310 | |2000 |6,070 |
|1750 |791 | |2005 |6,454 |
|1800 |978 | |2008 |6,707 |
(2) Use Table 1 to estimate the doubling times of Earth’s human population. Start with the year given below and estimate how long it took for the population in that year to double. The first entry is done for you. Be prepared to explain how you got your answers.
|Year |Doubling Time |
|8,000 BCE |2,000 years |
|6,000 BCE |(a) |
|3,000 BCE |(b) |
|AD 1 |(c) |
|1800 AD |(d) |
|1850 AD |(e) |
|1900 AD |(f) |
|1965 AD |(g) |
(3) Discuss the results from Question 2 with your group. What do you notice about the doubling times? What does this tell you about how the human population has changed over time?
One of the skills you will learn in this course is how to write quantitative information. A writing principle that you will use throughout the course is given below followed by Question 4, which gives you examples of how to use this principle.
Writing Principle: Use specific and complete information. The reader should understand what you are trying to say even if they have not read the question or writing prompt. This includes
• information about context, and
• quantitative information.
(4) Which of the following statements best describes the change in doubling times before 1800 AD?
(a) The doubling times decreased.
(b) Before 1800 AD, estimated population doubling times decreased from 2,000 to 1,000.
(c) The doubling times decreased from 2,000 to 1,000.
(5) Write a statement that describes the change in doubling times after 1800 AD.
Making Connections
Record the important mathematical ideas from the discussion.
Further Applications
(1) Imagine that you are explaining the relationship of million, billion and trillion to someone else. You may use words, symbols, and pictures. Your explanation should follow the Writing Principle.
Student Notes
Making Connections to the Lesson
(1) Which of the following was one of the main mathematical ideas of the lesson?
(i) The human population is quickly growing.
(ii) It is important to take time to make sense of large numbers because they occur in many important situations.
(iii) There are 5,280 feet in 1 mile.
(iv) There is not much difference between a million and a billion.
The purpose of the next question is to help you review previous lessons and understand how the mathematical ideas connect across lessons.
(2) Communication is an important skill in quantitative literacy. In Lesson 1.1, you saw how changes in wording can change the meaning of a statement. In Lesson 1.2, you learned about a writing principle to be used when writing about quantitative information. Two statements are given below. Give at least two reasons why Statement 2 is better than Statement 1.
Statement 1: The population doubled in about 40 years.
Statement 2: The world population doubled from 1960 to 2000 from about 3 billion people
to 6 billion.
Developing Skills and Understanding
(3) Which of the following statements is true?
(i) A trillion is 100 billion.
(ii) A trillion is 10 billion.
(iii) A trillion is 1,000 billion.
(iv) A trillion is 1010.
(4) Refer back to the table in Question 2 of Lesson 1.2. One of your classmates estimates the doubling time to be 500 years in 1000 AD. Does that answer seem reasonable? Meaning, does that number fit in with the numbers you see in your table? Write one or two sentences supporting your statement. Use the Writing Principle from the lesson.
(5) Some types of investments—such as Certificates of Deposit—earn interest based on a percentage rate. People often estimate the doubling time of investments to predict how much money the investment will be worth in the future. An investment that earns 4% interest will double in value about every 18 years. Use this information to complete the missing values in the table below for $2,500 invested at 4% interest.
|Year |Value of Investment |
|2000 |$2,500 |
| |$5,000 |
| |$10,000 |
|2054 | |
(6) Which of the following is the best estimate for the amount of time it would take the investment in Question 5 to reach a hundred thousand dollars?
(i) Less than 85 years
(ii) Between 85 and 95 years
(iii) Between 95 and 105 years
(iv) More than 105 years
Making Connections Across the Course
The OCE for Lesson 1.1 explained the purpose of the different sections of the assignments. Refer back to that information to answer the following questions.
(7) The first section of every assignment is called “Making Connections to the Lesson.” The purpose of this section is to
(i) help you identify and remember the important mathematical ideas of the lesson.
(ii) help you make a personal connection to the material in the lesson.
(iii) help you review all the work you did in the lesson.
(8) Which of the following are ways to use the “Developing Skills and Understanding” section to support your learning? There may be more than one correct answer.
(i) To earn points to improve your grade.
(ii) This section is not important unless you did not understand the work in class.
(iii) To assess how well you understand the new material from class.
(iv) To review information from previous lessons.
(9) Why do you rate yourself in the “Preparing for the Next Lesson” section? There may be more than one correct answer.
(i) So you can show the instructor how much you know.
(ii) To honestly assess if you are ready for the next class.
(iii) To get the best rating in class.
(iv) So you know what is expected in the next class.
It is not enough to complete the rating in the “Preparing for the Next Lesson” section of the assignment. First, you should use the rating to get ready for your next lesson. If your rating is a 3 or below, you should get help with the material before class. Remember, your instructor is going to assume that you are confident with the material and will not take class time to answer questions about it. If you need help, you should see your instructor or a tutor before class. You might also consider setting up a study group with classmates so you can help each other.
Second, you should use this rating to help you get better at self-assessment. Just like any other skill, being good at self-assessment takes practice. If you rate yourself as confident but then find that you are not prepared for class, you are not doing a good job of self-assessment. In this case, it is a good idea to talk to your instructor or a tutor about how you can do a better job of assessing yourself and preparing for class.
(10) Self-Regulated Learning: Reflect
Self-regulating your learning includes looking back and reflecting on what you understand. At the end of OCE 1.1, you rated your confidence in applying the mathematical skills listed below. After applying those skills in this assignment, has your confidence that you can successfully apply those skills changed? Use the following descriptions to rate yourself:
5—I am extremely confident I can do this task.
4—I am somewhat confident I can do this task.
3—I am not sure how confident I am.
2—I am not very confident I can do this task.
1—I am definitely not confident I can do this task.
|Skill or Concept: I can … |Rating from 1 to 5 |
|Double values in contextual situations. | |
|Identify place value to the trillions. | |
|Read a table of numbers. | |
|Add and subtract numbers. | |
Did your ratings change? If so, why?
Preparing for the Next Lesson (1.3)
Make sure you bring this work to class in case you need to refer back to it.
Read the following introduction to Lesson 1.3.
In this course, you will talk about different types of estimation.
• Educated guess: One type of estimation might be called an “educated guess” about something that has not been measured exactly. In Lesson 1.2, you used estimations of the world population. This quantity cannot be measured exactly—it would be impossible to count how many people live on the earth at any given time. Scientists can use good data and mathematical techniques to estimate the population, but it will always be an estimate.
• Convenient estimation: Sometimes estimations are used when it is inconvenient or not worthwhile to make an exact count. Imagine that you need to know how much paint to buy to paint the baseboard trim in your house. (The baseboard trim is the piece of wood that follows along the bottom of the walls.) You need to know the length of the baseboard. You could measure the length of each wall to the nearest 1/8 inch and carefully subtract the width of halls and doors. It would be much quicker and just as effective to measure to the nearest foot or half foot. If you were cutting a piece of baseboard to go along the floor, however, you would want an exact measurement.
• Estimated calculation: This usually involves rounding numbers to make calculations simpler. Lesson 1.3 focuses on estimating and calculating percentages. You will find in this course that percentages are used in many contexts. One of the most important skills you will develop is understanding and being comfortable working with percentages in a variety of situations.
The following questions will help you prepare for Lesson 1.3 by reviewing some concepts about percentages.
(11) Each large square below represents 100%. Use the squares to shade the indicated percentages and/or answer the questions.
(a) Shade 35% of the square below. What percentage is not shaded?
| | | |
|[pic] |1% |0.01 |
|[pic] | | |
| | |0.2 |
| |25% | |
|[pic] | | |
| |round to the nearest one percent | |
| | |round to nearest hundredth |
| | |0.5 |
|[pic] | | |
| |round to the nearest one percent |round to nearest hundredth |
| | |0.75 |
(13) Since money and percent are both based on 100, it is easy to think in terms of money and convert to fractions and decimals. For example, a dime is 10 cents, or $0.10, and 10 dimes is 1 dollar, so
1 dime is 1/10 of a dollar. Therefore, the expression “1/10 is 0.10” is the benchmark. Use money ideas to write similar benchmarks:
(a) penny
(b) nickel
(c) quarter
(d) half dollar
(e) dollar
(14) The connection between money and percent is similar. In the same way that 1 cent is 1/100 of a dollar, then 1% is 1/100 of the unit 1. Think “% can be replaced by 1/100.” Similarly, 100 cents is
1 dollar and 100% is the same as the number 1 (100% = 1). This is helpful in converting between decimals and percents. For example,
Percent to decimal: 35% = [pic] = 0.35
Decimal to percent: 0.72 = 0.72(1) = 0.72(100%) = 72%
For each of the following, convert between percent and decimal forms.
(a) Convert 45% to a decimal.
(b) Convert 0.125 to a percent.
(c) Convert 0.5% to a decimal.
(15) You should be able to do the following things for the next class. Rate how confident you are on a scale of 1–5 (1 = not confident and 5 = very confident).
Before beginning Lesson 1.3, you should understand the concepts and demonstrate the skills listed below:
|Skill or Concept: I can... |Rating from 1 to 5 |
|Understand the meaning of percent. | |
|Convert between fractions, decimals, and percentages. | |
|Round numbers to a given place value. | |
Specific Objectives
Students will understand that
• estimation is a valuable skill.
• standard benchmarks can be used in estimation.
• there are many strategies for estimating.
• percentages are an important quantitative concept.
Students will be able to
• use a few standard benchmarks to estimate percentages (i.e., 1%, 10%, 25%, 33%, 50%, 66%, 75%).
• estimate the percent one number is of another.
• estimate the percent of a number, including situations involving percentages less than one.
• calculate the percent one number is of another.
• calculate the percent of a number, including situations involving percentages less than one.
Problem Situation: Estimations with Percentages
In your previous out-of-class experience, you read about the importance of estimation. Strong estimation skills allow you to make quick calculations when it is inconvenient or unnecessary to calculate exact results. You can also use estimation to check the results of a calculation. If the answer is not close to your estimate, you know that you need to check your work.
In this course, you will make estimations and explain the strategies you used to generate estimations. There is not one best strategy. It is important that you develop strategies that make sense to you. A strategy is wrong only if it is mathematically incorrect (like saying that 25% is 1/2). In the following section, you will practice your use of estimation strategies to answer the questions and calculate percentages.
Use estimation to answer the following questions. Try to make your estimation calculations mentally. Write down your work if you need to, but do not use a calculator. First, complete the problem yourself. When you complete the problem, discuss your estimation strategy with your group. Your group should discuss at least two different strategies for each problem.
(1) You are shopping for a coat and find one that is on sale. The coat’s regular price is $87.99. What is your estimate of the sale price based on each of the following discounts?
(a) 20% off
(b) 25% off
(c) 35% off
(d) 70% off
Estimations help you make calculations quickly in daily situations. This next problem shows how estimates of percentages can be used to make comparisons among groups of different sizes.
(2) A law enforcement officer reviews the following data from two precincts. She makes a quick estimate to answer the following question: “If a violent incident occurs, in which precinct is it more likely to involve a weapon?” Make an estimate to answer this question and explain your strategy.
|Precinct |Number of Violent Incidents |Number of Violent Incidents |
| | |Involving a Weapon |
|1 |25 |5 |
|2 |122 |18 |
| | | |
(3) You have a credit card that awards you a “cash back bonus.” This means that every time you use your credit card to make a purchase, you earn back a percentage of the money you spend. Your card gives you a bonus of 0.5%. Estimate your award on $462 in purchases.
From Estimation to Exact Calculation
Being able to calculate with percentages is also very important. In the situation in Question 1, an estimate of the sale price will help you decide whether to buy the coat. However, the storeowner needs to make an exact calculation to know how much to charge. In Question 2, an estimate helps the officer get a sense of the situation, but if she is writing a report, she will want exact figures.
Calculate the exact answers for the situations in Questions 1–3. You may use a calculator. Show your work.
(4) If the coat’s regular price is $87.99, what is the exact sale price based on each of the following discounts?
(a) 35% off
(b) 25% off
(c) 70% off
(5) For each precinct, what is the exact percentage of incidents that involve a weapon? Round your calculation to the nearest 1%.
(6) Calculate the exact amount of your “cash back bonus” if your credit card awards a 0.5% bonus and you charge $462 on your credit card.
Making Connections
Record the important mathematical ideas from the discussion.
Further Applications
(1) Estimate an answer to each of the following. Explain your estimation strategy.
(a) 62% of 87
(b) 22% of 203
(c) 37 is what percent of 125
(d) 2 is what percent of 310
Student Notes
Making Connections to the Lesson
(1) Which of the following was one of the main mathematical ideas of the lesson?
(i) Percentages are used to calculate sale prices.
(ii) To calculate 35% of a number, multiply the number by 0.35.
(iii) Percentages are a ratio of a number out of 100. For example, 16% means 16 out of 100.
(iv) You should always calculate percentages exactly.
(2) Refer back to Lessons 1.1 and 1.2. Which statement below is a good description of how the important mathematical ideas of Lessons 1.1 and 1.2 connect to this lesson (1.3)?
(i) Many people worry that the world population is growing too rapidly. The rate of growth has been increasing throughout history.
(ii) Estimation is used in quantitative reasoning for many things, including estimating measurements, understanding large numbers, and making quick mental calculations.
(iii) Large numbers are hard to understand.
(iv) Calculating percentages is an important skill in quantitative reasoning because percentages are used in many situations.
Developing Skills and Understanding
Reference Information on Percentages, Fractions, and Estimation
There are many ways to do calculations with percents. The following videos and websites show some examples of methods.
• Calculate the percentage rate:
video/solving-percent-problems-2?playlist=Developmental Math
• Finding the percent of a number: science/files/percentofa/number.html
• Both problems types:
modules/percntof.htm
Language of Percentages and Fractions
There are several important vocabulary words you should know and use.
• A ratio is a comparison of two numbers by division. You will see many different types of ratios in this course. In this lesson, you worked with a special type of ratio called a percentage. A percentage is a ratio because it is a number compared to 100.
• Percentages are a relationship between two values: the comparison value and the reference value. The relationship is described as a percentage rate, which is shown with a percentage symbol (%). This indicates that the rate is out of 100.
Example: 10 is 20% of 50.
10 is the comparison value.
50 is the reference value.
20% is the percentage rate; it can be written as a decimal by using the relationship to 100: [pic]
• Fractions have two parts: [pic]
• Every fraction can be written in equivalent forms (e.g.,[pic]). It is often useful to write the fraction in the form with the smallest numbers. This is called simplified or reduced. In the example, [pic] is in simplest form.
The Language of Estimation
Certain words or phrases are often used to indicate that a number is an estimate rather than an exact figure. Read the following statement: “Almost 30% of the patients had less pain.” The word almost indicates that the percentage was a little less than 30. Some words and phrases that are commonly used to signal estimates are shown below.
|almost |about |approximately |
|more than |less than |close to |
|just over |just under |nearly |
(3) At Gillway Community College, 43 out of 381 students earned honors. At Montessa Valley Community College, 17 out of 108 students earned honors.
(a) Estimate the rate at which Gillway CC students earned honors.
(b) Estimate the rate at which Montessa Valley CC students earned honors.
(c) Which school had a higher rate of students earning honors?
(d) Write a statement about the estimated percentage of students who earned honors at Gillway CC. (Use a word or phrase from the list above.) You may want to refer to the Writing Principle from Lesson 1.2 and the handout on writing about quantitative information.
(4) Select all of the options that are either exactly equal to the given ratio or a good estimate of the ratio. There may be more than one correct answer.
(a) 60%
(i) 1 out of 6
(ii) 1 out of 60
(iii) 6 out of 10
(iv) close to [pic]
(v) 6 out of 100
(b) 8 out of 1,000
(i) less than 1%
(ii) about 8%
(iii) about [pic]
(iv) more than 8%
(v) 0.8%
(c) [pic]
(i) less than 1%
(ii) almost 10%
(iii) 8 out of 10
(iv) 2 out of 25
(v) 80%
For the situations in Questions 5–8, decide if it would be more appropriate to make an estimate or to do an exact calculation. Give your answer, and specify if the number represents an estimate or a calculation.
(5) Your bill at a restaurant is $23.17. You want to leave about 20% for a tip.
(a) How much should you leave?
(b) Is the answer an estimate or calculation?
(6) You are completing a tax form. The tax is 15.3% of $47,000.
(a) How much do you have to pay?
(b) Is the answer an estimate or calculation?
(7) During an election for city council, you hear a candidate say that 68% of children in the city live in poverty. You know that your children’s school has about 1,200 students.
(a) Based on the candidate’s statement, about how many children in the school live in poverty?
(b) Is the answer an estimate or calculation?
(8) You are a teacher and are grading a test. A student got 42 out 58 points.
(a) What is the student’s grade as a percentage?
(b) Is the answer an estimate or calculation?
(9) Some checking accounts pay a small amount of interest on the money in the account. In this case, interest is money that is paid to the account holder by the financial institution issuing the checking account. The interest is a percentage of the amount of money in the account. The percentage is called the annual interest rate. Compare the following two offers.
• Bank of Avalon pays 0.8% with no annual fee.
• Cypress Savings pays 1.5%, but charges a $10 annual fee.
Which would be the better offer if you have $1,000 in an account for 1 year?
Making Connections Across the Course
(10) There are about 300 million people in the United States. A 2007 report[7] claimed that the richest 1% of Americans controlled 42% of the nation’s wealth. About how many people is this?
(i) 1,000,000
(ii) 3,000,000
(iii) 126,000,000
(11) The same report claims that the poorest 80% of Americans controlled only 7% of the nation’s wealth. About how many people is this?
(i) 7,000,000
(ii) 21,000,000
(iii) 240,000,000
(12) The nation’s wealth in 2007 was about $72 trillion dollars. About how much money did the richest 1% of Americans control? (Recall that they controlled 42% of the nation’s wealth.)
(i) $720,000,000
(ii) $5,000,000,000
(iii) $30,000,000,000,000
(iv) $56,000,000,000
Note: In later lessons, you will be asked to compute things such as the average wealth per person among the richest 1% of Americans.
Working with Large Numbers
Large numbers such as those used in Question 14 can be hard to read when written out as a number. In Lesson 1.2, you used exponents to write powers of 10. For example, 100,000,000,000 = 1011. You can use this idea to write other large numbers in the form of a number multiplied by a power of 10. For example, the number 124,000 can be written as 1.24 x 105. You can check that this is true by multiplying this expression out:
1.24 x 105
( 1.24 x 100,000
( 124,000
There are other ways that 124,000 could be written as a power of 10. For example, 12.4 x 104 is also equal to 124,000.
(13) Which of these are equal to 135,230,000,000? There may be more than one correct answer.
(i) 1.3523 x 1011
(ii) 1.3523 x 107
(iii) 13.523 x 1010
(iv) One hundred thirty-five billion, two hundred thirty million
(v) One hundred thirty-five million, two hundred thirty thousand
(14) Write 68,000,000 in equivalent forms as instructed below.
(a) as a number times 105
(b) as a number times 107
(c) in words
(15) Based on your self-regulated learning reading from OCE 1.1, when self-regulating your learning, what are the three phases you should go through?
(16) On which phase do experienced math students or mathematicians usually spend the most time?
(17) How does reflecting on how solving a problem went help you become a more efficient learner?
Preparing for the Next Lesson (1.4)
(18) Match the fractions to their equivalent percent form (rounded to the nearest percent).
|(a) [pic] |(i) 10% |
|(b) [pic] |(ii) 20% |
|(c) [pic] |(iii) 25% |
|(d) [pic] |(iv) 33% |
|(e) [pic] |(v) 50% |
|(f) [pic] |(vi) 67% |
|(g) [pic] |(vii) 75% |
(19) In the OCE for Lesson 1.1, you used a place-value chart for place values greater than 1. Place value also extends to the right of the decimal to represent numbers less than 1.
(a) Place the decimal point in the correct position in the place chart below. Complete the missing names in the chart.
| Hundred thousands | Ten thousands | Thousands |
|First Expression |Second Expression |Yes |No |
|5 x 7 |7 x 5 | | |
|8 – 4 |4 – 8 | | |
|10 ÷ 2 |2 ÷ 10 | | |
|20 ÷ 2 |[pic] | | |
Multiplying Fractions
| | |
|Recognize common fraction benchmarks and equivalent percent form. | |
|Round a whole number to a given place value. | |
|Perform calculations using a calculator. | |
|Understand the relationship of multiplication and division (dividing by 3 is the same| |
|as multiplying by 1/3). | |
|Convert between a fraction and its decimal form. | |
|Multiply fractions. | |
Specific Objectives
Students will understand that
• flexibility with calculations is an important quantitative skill.
• different methods of calculation are often possible and helpful.
Students will be able to
• write a calculation in at least two different ways based on
o equivalent forms of fractions/decimals.
o relation of multiplication and division.
o the Commutative Property. [knowing when the order of numbers can be reversed,
such as 3 + 4 = 4 + 3, but 3 – 4 ≠ 4 – 3]
o order of operations
o the Distributive Property. [5(3 + 4) = 5 x 3 + 5 x 4]
Problem Situation: Performing Calculations in Multiple Ways
The ability to solve problems in multiple ways is an important quantitative reasoning skill. Today’s lesson asks you to brainstorm different ways to find the answer to a question. This flexibility is important because different strategies are often useful in different situations. You saw in Lesson 1.3 that estimation strategies often depend on the specific numbers. This can also be true in calculations. Sometimes changing the order of operations or grouping operations in other ways can be helpful. It is important to know when you can make changes such as these and still make the correct calculations.
You will use information from the 2009 Consumer Expenditure Survey for today’s lesson. This survey provides detailed information about how American consumers spend money. It contains information about individuals and what they purchase. The survey also has information about a typical family’s income and what that family uses its money to buy. The survey refers to each family as an “average household.”
The 2009 Consumer Expenditure Survey studied how Americans spend their income. (An expenditure
is something you spend money on.) The survey found that the average household had an income of $62,857. The survey also found that the average household spent about one-third (1/3) of its income on housing. This expenditure was either rent, if the family rented a home, or mortgage payments, if the family owned its home.[8]
You will use the information summarized above to answer the following questions.
(1) Estimate how much the average household spent on housing. Try to do the estimate mentally (without writing it down or using a calculator) if you can. Explain your strategy for your estimation. (Note: It is okay if people in your group use different strategies and for your estimates to be different.)
(2) How would you write a mathematical expression to find how much the average household spends on housing? (16.4 x 32 is an example of a mathematical expression.) Try to find as many different statements as possible.
(3) If one-third of expenditures went to housing, what fraction went toward other expenses?
(4) How could you calculate the amount spent on expenses other than housing? Think of as many different ways as you can.
(5) Which of the methods from Question 4 makes the most sense to you? Explain why. (Note: Your answer does not have to agree with your group.)
(6) The Montero family has the following average monthly expenses. Calculate how much they spend on housing (this includes rent and utilities) in one year.
|Rent |$1,250 |
|Electricity |$85 |
|Gas |$120 |
|Water and sewer |$72 |
(7) Look at your answer in Question 6. Does it seem reasonable? Reasonable often means that your answer is not too big or too small to make sense. Write a short sentence about why your answer is reasonable. If your answer is not reasonable, check your calculations.
Making Connections
Record the important mathematical ideas from the discussion.
Further Applications
(1) The graph on the following page represents the budget of an average college student according to Westwood College.[9] Write three questions about these data that require calculations or estimation. You may refer to Questions 1–4 in the lesson for examples. Include the answers to your questions. (Note: You may need to make up amounts to represent a student budget, as that information is not given.)
[pic]
Student Notes
Making Connections to the Lesson
(1) Which of the following was one of the main mathematical ideas of the lesson?
(i) You can change a calculation in any way that you think will make it easier to do.
(ii) Calculations can often be performed in different ways based on mathematical rules.
(iii) Multiplying by [pic] is the same as multiplying by 2 and then dividing by 3.
(iv) The average household spends about 33% of its income on housing.
(2) Lessons 1.3 and 1.4 both emphasized that there are different ways to approach problems. This is true for both estimation and calculations. The best strategy depends on the situation, the numbers used, and the way you think. Select one question from each lesson that is an example of this idea.
|Lesson |Question |Show at least two ways to do the problem. |
| |Number | |
|1.3 | | |
| | | |
| | | |
|1.4 | | |
| | | |
| | | |
Developing Skills and Understanding
In Lesson 1.4, you used several important mathematical rules and relationships to perform calculations in different ways. Those rules are summarized for you here so you can refer back to them. The authors are also introducing the formal names for the rules. You do not have to memorize these names for this course, but you may use them in other math classes. If you want more help with any of the rules, use the formal names to find resources on the Internet.
Mathematical rules are defined in terms of variables. The variables are symbols, usually letters, that represent numbers. You use variables to show that the rule can apply to multiple numbers. This is called generalizing because it shows that a rule can be used in general and not just in specific cases. The rule using both variables and numbers will be shown.
While mathematical rules are very important, in this course, the authors emphasize reasoning over memorizing rules. As you review the rules, try to make sense of the rules so that they will become a part of your thinking.
Commutative Property
The order of addition and multiplication can be changed.
|General Rule |Example |
|a + b = b + a |8 + 3 = 3 + 8 |
|a x b = b x a |5 x 6 = 6 x 5 |
It is important to remember that the Commutative Property does not apply to subtraction and division.
Order of Operations
The order of operations defines the order in which operations are performed.
|General Rule |Example |
|1. Operations within grouping symbols, innermost first. Grouping |15 + [12 – (3 + 2) ] – 2 × 32 ÷ 6 |
|symbols include |15 + [12 – (5) ] – 2 × 32 ÷ 6 |
|Parentheses ( ) |15 + [7] – 2 × 32 ÷ 6 |
|Brackets [ ] | |
|Fraction Bar | |
|2. Exponents |15 + [7] – 2 × 9 ÷ 6 |
|3. Multiplication and division, left to right |15 + [7] – 18 ÷ 6 |
| |15 + [7] − 3 |
|4. Addition and subtraction, left to right |22 – 3 |
| |19 |
Distributive Property
The Distributive Property is easiest to understand by looking at examples.
|General Rule |Example |
|a (b + c) = a × b + a × c |4 (3 + 1) = 4 × 3 + 4 × 1 |
|Note about subtraction: Subtraction is related to addition. The |To demonstrate that these two calculations are equivalent, each |
|Distributive Property is shown using addition, but it also works |side is done separately. |
|with subtraction as shown below: |Left side: Using order of operations, the operation inside the |
|8 (5 – 1) = 8 × 5 – 8 × 1 |parentheses is done first. |
| |4 (3 + 1) |
|Notation: The operation of multiplication is shown in many ways. |4 (4) |
|You have already seen the use of the multiplication symbol (x). |16 |
|Another way to indicate multiplication is a number or variable in|Right side: Using the Distributive Property, the multiplication |
|front of parenthesis with no other symbol. For example: |is distributed over the addition. |
|6(2) = 6 x 2 |4 (3 + 1) |
|a(b) = a x b |4 × 3 + 4 × 1 |
|You will learn other symbols for multiplication later in the |Order of operations tells you to multiply first. |
|course. |12 + 4 |
| |16 |
Division
Division is the same as multiplication by the reciprocal. You get the reciprocal of a number when you write the number as a fraction and reverse the numerator (the top number) and the denominator (bottom number).
|General Rule |Example |
|a ÷ b = a × [pic] |15 ÷ 5 = 15 × [pic] |
|a ÷ [pic] = a × [pic] |10 ÷ [pic] = 10 × [pic] |
(3) In Lesson 1.4, you saw that there was a relationship between multiplication and division. Refer back to this work to complete the following statement.
62,857 ( 3 is the same as [pic]
(4) Using the concept from the previous question, fill in the blanks to create equivalent statements.
|Multiplication |Division |
|85 × [pic] |85 ÷ [pic] |
|1.23 × [pic] |1.23 ÷ 7 |
|1.23 × [pic] |1.23 ÷ [pic] |
(5) Which expressions are equivalent to 16 x [pic]? There may be more than one correct answer.
(i) 16 x 3 ( 4
(ii) 16 ( 0.75
(iii) 3 x 16 ( 4
(iv) 3 ( 4 x 16
(v) 16 x 0.75
(vi) 16 ( 4 x 3
(vii) 0.75 x 16
(viii) 16 x 4 ( 3
(6) According to the Consumer Expenditure Survey, the average American household spent $6,372 on food in 2009. About two-fifths of that was spent on eating out at restaurants. Calculate two-fifths of $6,372 to estimate the amount that was spent on eating out.
Introduction to Spreadsheets
A spreadsheet is a computer program used to organize and analyze data. In the example below, Lisa has created a spreadsheet for her monthly budget. Data is entered into cells, like the boxes in a table. The cells are named by the letter of the column along the top and numbered rows down the side. Note the cell that contains the word income is labeled as A2, not 2A.
[pic]
Use this spreadsheet to answer Questions 7–9.
(7) What is in Cell B4?
(8) What does the number in Cell B4 represent in Lisa’s budget?
(i) The money she plans to spend on rent each month.
(ii) The money she plans to spend on utilities each month.
(iii) The money she plans to spend on food each month.
(iv) The money she plans to spend on insurance each month.
(v) The money she plans to spend on gas for her car each month.
Formulas can be used to perform calculations in spreadsheets. The formulas use the cell name as a variable that represents the value in that cell. For example, in the spreadsheet above, the formula =B3+B4 would result in the calculation 750 + 230, and $980 would be displayed. Spreadsheets are
a valuable tool because once a formula is written, its result changes when the values change. So if
Lisa’s rent increases, she can change the number in Cell B3. The formulas calculate the new results automatically.
(9) Lisa put the following formula in her spreadsheet: = B2 – B3 – B4 – B5 – B6 – B7.
(a) Calculate the result of this formula.
(b) What does this value represent for Lisa?
(i) The amount of money she expects to lose each month.
(ii) The amount of money she expects to have left after paying bills each month.
(iii) The percentage of her income that she will be able to save each month.
(iv) The value has no meaning for Lisa.
(c) Which of the following expressions would give the same result as Lisa’s formula? There may be more than one correct answer.
(i) = B2 – B3 + B4 + B5 + B6 + B7
(ii) = B2 – (B3 + B4 + B5 + B6 + B7)
(iii) = (B3 + B4 + B5 + B6 + B7) – B2
Making Connections Across the Course
(10) Which of these expressions show ways to calculate 25% of 2,310? There may be more than one correct answer.
(i) 2,310 ( 4
(ii) 2,310 x 4
(iii) 2,310 ( 25
(iv) 2,310 x 25[pic]
(v) 2,310 x 0.25
(vi) 2,310 ( 0.25
(vii) [pic] x 2,310
(viii) [pic] ( 2,310
(ix) 0.25 x 2,310
(x) 0.25 ( 2,310
(11) Which expression is the same as 20% of a billion? There may be more than one correct answer.
(i) 0.2 x 1,000,000,000
(ii) 0.2 x 1,000,000
(iii) 109 ( 5
(iv) 109 ( 20
(v) 106 ( 5
(vi) One-fifth of 1,000 million
(vii) 20,000,000
(viii) 20 ( 100 x 1,000,000,000
Scientific Notation
In OCE 1.3, you saw that a large number can be written as a number times a power of 10 in many different ways. For example, the number 124,000 can be written as 1.24 x 105 or 12.4 x 104. These different forms are all equivalent.
Scientific notation is a very specific way to write a large number as a power of 10. The purpose of scientific notation is to make it easier for people to use and communicate with large numbers. It would be confusing if two people working together on one project wrote the same number in two different ways. To avoid this, people decided that numbers in scientific notation would always be written in the same way: a number between 1 and 10 times a power of 10.
From the previous example:
• 1.24 x 105 is in scientific notation because 1.24 is a number between 1 and 10.
• 12.4 x 104 is not in scientific notation because 12.4 is larger than 10.
Write each of the following numbers in scientific notation.
(12) 16,900,000
(13) 4,275,000,000
Self-Regulating Your Learning: The Plan Phase
At the start of this module, the authors briefly described what it means to be a “self-regulated learner.” As you already learned, being a self-regulated learner involves going through three phases when you are working on a problem or an assignment. The phases are
1. Plan
2. Work
3. Reflect
In this lesson, you will look at what you should be doing during the Plan phase. As you might imagine, the planning phase involves thinking about all the things you need to do to successfully complete a problem or assignment before you begin working on it. As was said previously, researchers who study how people learn found that experts often spend a lot more time planning how they are going to finish a task than they spend actually doing the task.
The planning phase involves several important aspects. The following are some that will be explored in this course:
• How much confidence you have that you can successfully complete the problem.
• The amount of time and effort you think it will take to understand and work on the problem.
• The strategies you might use to solve the problem.
• The goals you have as you try to work on the problem.
The authors will now describe each aspect in a little more detail. You will also continue to revisit them throughout the rest of the course.
Confidence: People who study how you learn have found that your beliefs regarding your ability to do a given task, like work a particular math problem, often predicts how well you actually do. Here is one way to think about it: If you really believe you can succeed at a problem, you are more likely to keep trying and keep working on that problem even if you get stuck. Because you invest more effort, you are more likely to be successful. On the other hand, if you look at a problem and immediately think “I cannot do this,” then when you do get stuck or confused, you might be more likely to give up and not be successful. Researchers call your beliefs about your abilities your self-efficacy.
In this course, you will be asked to rate your self-efficacy on certain problems. If you rate yourself low, then you might want to allow more time to do that problem, plan to go get help, or try being more patient than you might normally be. Thinking about your confidence can help you plan your time and effort when you work on a problem or task.
Time and Effort: Obviously, some problems or assignments take more time than others. Some assignments require more effort than others. It can be frustrating to jump into an assignment thinking you can finish it easily or quickly only to discover it is harder or takes way more time than you thought it would. You can avoid some or all of that frustration if you have a realistic idea of how hard the assignment will be. Also, having a good idea of how much time and effort will be needed helps you manage your time. For example, you might need to allocate time to discuss the assignment with your instructor, classmates, or tutors. For these reasons, approximating the time and effort needed before starting work on an assignment is a good planning tool.
Strategies: When you start working on a problem or assignment, you often have to try several different strategies before you find an approach that will help you complete it successfully. Sometimes, it is the first strategy you think of, but often it is not. If you think about possible strategies before you begin working, you immediately have another one to try if your first one does not work. Self-regulated learners think about many different possible strategies, and then begin trying to solve a problem.
Goals: Education researchers have shown that students who have “learning goals,” are more likely to succeed than students who have what are called “performance goals.” If you have learning goals, you are trying to understand what you are learning and trying to make connections between ideas and concepts. If you have performance goals, you care most about finishing an assignment to get points or have it done; you are not focused on understanding the material. Self-regulated learners try to have learning goals more than performance goals. This helps them stay focused and motivated to learn when the problems are challenging. Good planning means making an effort to change your thinking so you have learning goals as often as possible.
In future lessons and assignments, you will have opportunities to practice the planning ideas presented here. Before then, start incorporating the planning phase whenever you start an assignment. If you do, you will be better prepared and more likely to succeed.
Preparing for the Next Lesson (1.5)
(14) Which expressions are ways to write the number 5,200,000? There may be more than one correct answer.
(i) 52 million
(ii) 5.2 billion
(iii) 5.2 million
(iv) Five million, two hundred thousand
(v) Fifty-two million
(vi) 5,200
(15) Estimate the following percentages without using a calculator.
(a) 10.1% of 7,800
(b) 0.99% of 83,583
(c) 20% of 5,008,340
(d) 0.52% of 472,028
(16) Which expressions are equivalent to [pic]? There may be more than one correct answer.
(i) [pic]
(ii) [pic]
(iii) [pic]
(iv) [pic]
(v) [pic]
The following information will be used in Lesson 1.5. You will be given some information about how much you have to pay to borrow money on a credit card. The company charges interest on the amount that you do not pay off each month. This is called your balance. Interest is based on a percentage of the amount you have borrowed. The annual interest rate is the APR (annual percentage rate.)
Creditworthiness is how likely it is that you will pay your bills on time. It is measured by a credit score that can range from 300 to 850. Someone with a high credit score has good credit and will get a lower interest rate than someone with a low credit score.
Credit cards are very complicated. Because it is important for people to understand how much credit cards charge, the U.S. government has a law called the Credit Card Accountability, Responsibility, and Disclosure Act of 2009, which requires companies to publish information about rates and fees in a standard format. This is called a disclosure or the pricing and terms.
The disclosure begins with a summary like the one shown below. Scan this form. (This means to read it quickly to get a general sense of the information without trying to understand every detail.) This information will be discussed in more detail in Lesson 1.5.
|Interest Rates and Interest Charges |
|Annual Percentage Rate |0.00% introductory APR for 6 months from the date of account opening. |
|(APR) for Purchases |After that, your APR will be 10.99% to 23.99% based on your creditworthiness. This APR will vary with the |
| |market based on the Prime Rate. |
|APR for Balance Transfers |0.00% introductory APR for 24 months after the first transaction posts to your account under this offer. |
| |After that, your APR will be 10.99% to 23.99% based on your creditworthiness. This APR will vary with the |
| |market based on the Prime Rate. |
|APR for Cash Advances |28.99%. This APR will vary with the market based on the Prime Rate. |
|Penalty APRs and When It |Between up to 16.99% and up to 26.99% based on your creditworthiness and other factors. |
|Applies |This APR will vary with the market based on the Prime Rate. |
| |This APR may be applied to new purchases and balance transfers on your account if you make a late payment. |
| |How long will the penalty APR apply?: If your APRs for new purchases and balance transfers are increased for a|
| |late payment, the Penalty APR will apply indefinitely. |
|How to Avoid Paying |Your due date is at least 25 days after the close of each billing period (at least 23 days for billing periods|
|Interest on Purchases |that begin in February). We will not charge you any interest on purchases if you pay your entire balance by |
| |the due date each month. |
|Minimum Interest Charge |If you are charged interest, the charge will be no less than $0.50. |
Are you prepared for Lesson 1.5?
(17) SRL: Plan
You should be able to do the following things for the next class. Rate how confident you are on a scale of 1–5 (1 = not confident and 5 = very confident).
Before beginning Lesson 1.5, you should understand the concepts and demonstrate the skills listed below:
|Skill or Concept: I can … |Rating from 1 to 5 |
|Name and understand large numbers written in different forms. | |
|Use benchmarks to estimate percentages including percentages less than 1%. | |
|Use order of operations and the Distributive Property to write expressions in | |
|different forms. | |
(18) SRL: Plan
The next lesson (1.5) will be a review of concepts in the course so far. After reading the information above about the Plan phase, think about what you might do to be well prepared for your next class session. Try to incorporate the ideas of confidence (self-efficacy), time and effort, strategies, and your goals. Write out your planning ideas. Your instructor may ask you to discuss this in class.
Specific Objectives
Students will understand that
• quantitative reasoning and math skills can be applied in various contexts.
• creditworthiness affects credit card interest rates and the amount paid by the consumer.
• reading quantitative information requires filtering out unimportant information (introductory level).
• course expectations regarding writing about mathematics in context.
Students will be able to
• recognize common mathematical concepts used in different contexts.
• apply skills and concepts from previous lessons in new contexts.
• identify a complete response to a prompt asking for connections between mathematical concepts and a context.
• write a formula in a spreadsheet.
Problem Situation: Understanding Credit Cards
When you use a credit card, you can pay off the amount you charge each month. If you do not pay the full amount, you are borrowing money from the credit card company. This is called credit card debt. Many people in the United States are concerned about the amount of credit card debt both for individuals and for society in general. In this lesson, you will use skills and ideas from previous lessons to think about some issues related to credit cards. You may want to refer back to the previous lessons.
(1) The statements below came from two websites that report predictions about credit card debt in 2010:
• “In 2010, the U.S. census bureau is reporting that U.S. citizens have over $886 billion in credit card debt and that figure is expected to rise to $1.177 trillion this year.”[10]
• The debt in 2010 is “expected to grow to a projected 1,177 billion dollars.”[11]
Do these two websites project the same amount of debt? Or did one of the websites make an error? Justify your answer with an explanation.
You will use the following information from the disclosure for Questions 2 and 3.
|Annual Percentage Rate (APR) |0.00% introductory APR for 6 months from the date of account opening. |
|for Purchases |After that, your APR will be 10.99% to 23.99% based on your creditworthiness. This APR will vary with the |
| |market based on the Prime Rate. |
(2) Creditworthiness is measured by a “credit score,” with a high credit score indicating good credit. In the following questions, you will explore how your credit score can affect how much you have to pay in order to borrow money. Juanita and Brian both have a credit card with the terms in the disclosure form given above. They have both had their credit cards for more than 6 months.
(a) Juanita has good credit and gets the lowest interest rate possible for this card. She is not able to pay off her balance each month, so she pays interest. Estimate how much interest Juanita would pay in a year if she maintained an average balance of $5,000 each month on her card. Explain your estimation strategy.
(b) Brian has a very low credit score and has to pay the highest interest rate. He is not able
to pay off his balance each month, so he pays interest. Calculate how much interest he would pay in a year if he maintained an average balance of $5,000 each month. Show your calculation.
(c) What are some things that might affect your credit score?
(3) The APR is an annual rate, or a rate for a full year. The APR is divided by 12 to calculate the interest for a month. This is called the periodic rate.
(a) What is the periodic rate for Juanita’s card? Round to two decimal places.
(b) Juanita has a balance of $982 on her January statement. Which of the following is the best estimate of how much interest she will pay?
|Less than a dollar |$5–$10 |$10–$20 |More than $20 |
| | | | |
(c) Explain your answer to Part (b).
You will use the following information from the disclosure for Question 4. A cash advance is when you use your credit card to get cash instead of using it to make a purchase.
|Annual Percentage Rate (APR) |After that, your APR will be 10.99% to 23.99% based on your creditworthiness. This APR will vary with |
|for Purchases |the market based on the Prime Rate. |
|APR for Cash Advances |28.99%. This APR will vary with the market based on the Prime Rate. |
(4) Discuss each of the following statements. Decide if it is a reasonable statement.
(a) Jeff pays the highest interest rate for purchases. For a cash advance, he would pay $0.05 more for each dollar he charges to his card.
(b) The interest for cash advances is about two-and-a-half times as much as for the lowest rate for purchases.
Brian used a spreadsheet to record his credit card charges for a month.
[pic]
Brian used the following expression to calculate his interest for these charges for one month.
[pic]
(5) Which of the following statements best explains what the expression means in terms of the context?
(i) Brian added his individual charges. Then he divided 0.2399 by 12. Then he multiplied the two numbers.
(ii) Brian found the interest charge for the month by dividing 0.2399 by 12 and multiplying it by the sum of Column B.
(iii) Brian added the individual charges to get the total amount charged to the credit card. He found the periodic rate by dividing the APR by 12 months and multiplied the rate by the total charges. This gave the interest charge for the month.
Making Connections
Record the important mathematical ideas from the discussion.
Further Applications
(1) Refer to Question 6 in the Lesson 1.5 OCE. Write an explanation of at least one estimation strategy that could have been used for each correct statement.
(2) Refer to the expression given in Question 3 of the Lesson 1.5 OCE. Why do you do the addition in the numerator before dividing by 12?
Student Notes
Making Connections to the Lesson
(1) Which of the following was one of the main mathematical ideas of the lesson?
(i) The number $1.177 trillion can also be written as $1,177 billion.
(ii) Credit cards are expensive to use if you do not pay off your balance each month. You pay more interest for cash advances than for the balance on purchases. Credit card debt is a problem in the United States.
(iii) A percentage is always a number greater than 1.
(iv) Understanding numbers includes knowing how numbers compare in size, knowing what numbers represent in situations, and using estimation to answer questions about numbers.
(2) Four lessons are listed below. In each lesson, you were asked to make sense of numbers in different ways. Find a specific example from the lessons. Use the first two as examples.
|Lesson |We made sense of numbers when we … |
|1.1 |Asked if the statistic on the sign was reasonable. |
|1.2 |Used the idea of lines of people to compare the size of a million to a billion. |
|1.4 | |
|1.5 | |
Developing Skills and Understanding
(3) Refer back to Question 5 in the lesson.
(a) A student used a different expression to calculate Brian’s monthly interest. Choose the sentence that best explains what the expression means in terms of the context and the order in which the calculations were done. Spreadsheets use an asterisk (*) to indicate multiplication: 3 * 4 means 3 times 4.
[pic][pic]
(i) Find the annual interest for each individual charge and then add to find the total annual interest. Divide by 12 months to find the interest for 1 month.
(ii) Distribute 0.2399 to the sum of the charges and then divide by 12.
(iii) Divide the annual interest rate by 12 to find the monthly interest rate and then multiply by each of the charges to find the monthly interest for each charge. Add the monthly interest for each charge to find the total monthly interest.
(iv) Multiply each entry in the B column by 0.2399. Add the results and divide by 12 to find the final answer.
(b) Open a spreadsheet program. Enter the information shown in Question 5 from the lesson. In which cell(s) should the formula for calculating the monthly interest be entered?
(i) C2 through C5
(ii) B7
(iii) B6
(iv) C7
(v) A6
(c) Enter the formula given in Question 5 into the correct cell. To do this, click on the cell. First
type =. (A formula in a spreadsheet always starts with an = sign.) Type the formula. Notice
as you type that your formula appears in the cell and also in the formula bar above the spreadsheet cells. Press enter. Record the result (what appears in the cell) when you are done.
(4) Refer back to Question 1 in the lesson.
(a) Write the projected debt in standard form (written as a number like 374,000).
(b) What is the projected debt in scientific notation?
(i) 1,177 x 109
(ii) 11.77 x 1012
(iii) 1.177 x 1012
(iv) 1.177 x 1011
(v) 11.77 x 1011
(5) The Federal Reserve has useful consumer information about credit cards. Go to the website creditcard. Select the option, “Learn more about your offer.” This is an interactive site in which you can get information by clicking on parts of the offer form. Use the information to answer the following questions.
(a) Which of the following can trigger a penalty annual percentage rate (APR)? There may be more than one correct answer.
(i) You are late in paying your bill.
(ii) You pay your bill too early.
(iii) You do not use the credit card for six consecutive months.
(iv) You go over your credit limit.
(b) Which of these statements are true? There may be more than one correct answer.
(i) A man has a car loan and a credit card with Great American Bank. He misses a payment on his car loan. Great American can charge the penalty APR on his credit card.
(ii) All credit cards charge an annual fee.
(iii) You do not pay interest on a cash advance until 25 days after the advance is made.
(iv) If you pay your bill late, in addition to paying a higher penalty rate, you will also pay a penalty fee.
(c) How can you avoid paying interest on purchases?
(i) Always make the minimum payment on time.
(ii) Avoid late fees.
(iii) Pay the entire balance by the due date.
(iv) Pay the minimum interest charge.
(d) Use the introductory APR shown in the disclosure on the website. How much more in interest would you pay in one year for a balance of $5,000 if you have a very low credit score compared to having a very high credit score?
(6) A college student is talking to her family about a February 1, 2010, news story she read at .[12] It states:
Florida college students could face yearly 15 percent tuition increases for years, and University of Illinois students will pay at least 9 percent more. The University of Washington will charge 14 percent more at its flagship campus. And in California, tuition increases of more than 30 percent have sparked protests reminiscent of the 1960s.
The student attends the University of California and paid about $7,800 in tuition in 2009. Which of the following statements is a good quantitative description of how her tuition will change based on the news story? There may be more than one correct answer.
(i) My tuition is going to increase by almost a third!
(ii) My tuition will go up by more than $2,000.
(iii) My tuition is going up a lot!
(iv) My tuition will be around $9,000.
(v) My tuition will be around $8,500.
Making Connections Across the Course
Big budget movies are tracked by investors and consumers. The following table gives data on the six movies with the largest budgets that had been released as of June 20, 2010.[13] The data includes an estimate of the U.S. gross earnings and worldwide gross earnings of movies. Gross earnings is the amount of money that a movie takes in.
|Release |Movie |Distributor |Budget |U.S. Gross Earnings |Gross Earnings Outside |
|Date | | | | |U.S. |
|5/25/2007 |Pirates of the |Buena Vista |$300,000,000 |$309,420,425 |$651,576,067 |
| |Caribbean: At World’s | | | | |
| |End | | | | |
|11/24/2010 |Tangled |Buena Vista |$260,000,000 |$200,821,936 |$385,760,000 |
|5/4/2007 |Spider-Man 3 |Sony |$258,000,000 |$336,530,303 |$554,345,000 |
|5/20/2011 |Pirates of the |Buena Vista |$250,000,000 |$220,746,502 |$731,900,000 |
| |Caribbean: On Stranger | | | | |
| |Tides | | | | |
|7/15/2009 |Harry Potter and the |Warner Bros. |$250,000,000 |$301,959,197 |$632,000,000 |
| |Half-Blood Prince | | | | |
|12/18/2009 |Avatar |20th Century Fox |$237,000,000 |$760,507,625 |$2,023,411,357 |
(7) Write the name in words for the gross earnings outside the United States for Avatar.
(8) Which of the following calculations shows a correct method to estimate the net earnings for Pirates of the Caribbean: At World’s End? Net earnings is the total amount the movie makes after expenses (the budget) are taken out. There may be more than one correct answer.
(i) ($310,000,000 + $650,000,000) – $300,000,000 = $660,000,000
(ii) $650,000,000 – ($310,000,000 + $300,000,000) = $660,000,000
(iii) The budget and the U.S. gross earnings are about the same and cancel each other out. The net earnings would be about the same as the gross earnings outside the United States, or about $650 million dollars.
(iv) The gross earnings are about $600 million plus $300 million, or $900 million. The expenses are about $300 million. So, the net earnings are about $600 million dollars.
(9) Refer to the data for Harry Potter and the Half-Blood Prince.
(a) Estimate the net earnings.
(b) Write two statements to explain a way to estimate the net earnings. One should be a numeric expression (as in 8i) and the other should be in words (as in 8iv).
(10) The return on investment is the percentage that the net earnings are of the budget. Which of the following statements best estimates the return on investment for Pirates of the Caribbean: At World’s End? There may be more than one correct answer.
(i) The net earnings for Pirates of the Caribbean: At World’s End were more than triple the investment.
(ii) The net earnings for Pirates of the Caribbean: At World’s End were more than double the investment.
(iii) The return on investment for Pirates of the Caribbean: At World’s End was more than 300%.
(iv) The return on investment for Pirates of the Caribbean: At World’s End was more than 200%.
(11) In OCE 1.4, you read about self-regulating your learning during the plan phase. Explain briefly why it is important to evaluate your confidence before planning on working a problem.
(12) From your previous reading about the plan phase, what is the difference between performance goals and learning goals? Explain why students with learning goals are often more successful.
Preparing for the Next Lesson (1.6)
(13) Which of the following can be used to represent 5 out of 20? There may be more than one correct answer.
(i) [pic][pic]
(ii) 0.25
(iii) 25%
(iv) 0.25%
(v) 25
(14) What is another way to represent 3/5? There may be more than one correct answer.
(i) 1.66
(ii) 166%
(iii) 60%
(iv) 0.6
(v) 6/10
(vi) 3 out of 5
(15) Which of the following is the standard form of 1.23 x 1011?
(i) 1,230,000,000,000
(ii) 123,000,000,000
(iii) 12,300,000,000
(iv) 1,230,000,000
Scientific Notation and Calculators
Scientific notation is useful because it is easy to make mistakes when working with numbers that contain a lot of zeros. You can use scientific notation with a calculator that has an exponent feature. Instructions for using exponents with two different types of calculators are given as follows.
Scientific Calculator: These calculators have a key that looks like one of the following:
or
The keystrokes for entering 108 are
Graphing Calculators and Computers: Graphing calculators and computers have a key that looks like the picture shown below. This is called a caret symbol. It is also used for exponents in computer programs, including spreadsheets.
The keystrokes for entering 108 are
Calculators automatically display results to calculations in scientific notation when the numbers have too many digits to be displayed on the screen. The way that these are displayed varies slightly with different calculators. One common display is 2.34 E9, which represents 2.34 x 109.
(16) As of 2011, the world population was estimated to be about 6.93 x 109. (Recall the discussion of scientific notation from the previous assignment.) About 4.5% of the world’s population lives in the United States. Approximately how many people live in the United States?
(i) 1.54 x 108
(ii) 3.1 x 109
(iii) 3.1 x 108
(iv) 1.54 x 109
(v) 3.1 x 107
(vii) 1.54 x 107
(17) Water usage varies greatly in different countries, from as little as 20 liters a day per person in some third world countries, to 600 liters a day in the U.S. How much water would be needed for one day if every person in the world used 50 liters of water a day?
(i) Write your answer in scientific notation.
(ii) Write your answer in standard notation (as a number).
(iii) Write your answer in words.
Background Information for the Upcoming Lesson
The following information will be used in Lesson 1.6. You will again examine the situation of the earth’s population. Recall in Lesson 1.2 that you looked at how the population has grown and is currently growing. As stated in Lesson 1.2, “Numerous scientists have conjectured about how long we can sustain ourselves, as we cruise the solar system in our self-contained environment.” One of the most important natural resources that humans need for survival is water.
An influential United Nations report published in 2003 predicted severe water shortages will affect
4 billion people by 2050. This report also said that 40 percent of the world’s population did not have access to adequate sanitation facilities in 2003[14]. You need clean water not just for drinking, but for necessary tasks such as sanitation, growing food, and producing goods.
You will use a measure of water consumption, called a “water footprint” that includes all of the ways that people use fresh water. According to , “The water footprint of an individual, business or nation is defined as the total volume of freshwater that is used to produce the goods and services consumed by the individual, business, or nation.”[15] Goods are physical products such as food, clothes, books, or cars. Services are types of work done by other people. Examples of services are having your hair cut, having a mechanic fix your car, or having someone provide day care for your children. Fresh water is often used to make goods and to provide you with services.
To prepare for your class, make sure you understand this information and understand the term water footprint. For more information, you can do an Internet search for “definition of water footprint.” Or, review the following two resources:
• “Forget carbon: you should be checking your water footprint” by Amol Rajan, April 21, 2008. independent.co.uk/environment/green-living/forget-carbon-you-should-be-checking-your-water-footprint-812653.html
•
Are you prepared for Lesson 1.6?
(18) Did you read and understand the information to be used in class?
(19) You should be able to do the following things for the next class. Rate how confident you are on a scale of 1–5 (1 = not confident and 5 = very confident).
Before beginning Lesson 1.6, you should understand the concepts and demonstrate the skills listed below:
|Skill or Concept: I can … |Rating from 1 to 5 |
|Calculate a quotient (one number divided by another). | |
|Use calculator to divide numbers. | |
|Use scientific notation. | |
|Convert between fractions, percents, and decimals. | |
Specific Objectives
Students will understand that
• the magnitude of large numbers is seen in place value and in scientific notation.
• proportions are one way to compare numbers of varying magnitudes.
• different comparisons may be needed to accurately compare two or more quantities.
Students will be able to
• express numbers in scientific notation.
• estimate ratios of large numbers.
• calculate ratios of large numbers.
• use multiple computations to compare quantities.
• compare and rank numbers including those of different magnitudes (millions, billions).
Problem Situation 1: Comparing Populations
In your out-of-class experience, you read about a “water footprint.” In this lesson, you are going to compare the populations of China, the United States, and India. You will go on to look at the water footprint for each nation as a whole and per person (“per capita”) to make some comparisons and to consider what this information might mean for the planet’s sustainability—that is, Earth’s ability to continue to support human life. While there is no one definition of sustainability, most agree that “sustainability is improving the quality of human life while living within the carrying capacity of supporting eco-systems.” Carrying capacity refers to how many living plants, animals, and people
Earth can support into the future.
You will begin by thinking of various ways you can compare different countries’ populations. Scientific notation might be a useful tool because it is a way to write large numbers. A number in scientific notation is written in the form: a x 10n where 1 ≤ a < 10; and n is an integer.
Examples
• 28,930,000 can be written in scientific notation as 2.893 x 107.
• In 2011, the population of the world was approximately 6.9 billion people. You can write this as 6,900,000,000 or you can use scientific notation to write it as 6.9 x 109 people.
(1) In 2011, the population of the United States was 311,000,000. Earth’s population was about
7 billion. Write these numbers in scientific notation.
(2) What are some other ways you could compare the population of the United States to the population of Earth? Think about forms of comparisons using both estimation and calculation.
(3) In 2011, the population of China was 1.341 billion. Compare China’s 2011 population to the world population with a ratio. Write your answer as a percent and as a fraction. Consider how many decimals to give in your final answer.
(4) Compare China’s population with the population of the United States using a ratio with the U.S. population as the reference value. Write a sentence that interprets this ratio in the given context.
Problem Situation 2: Comparing Water Footprints
The population of the United States is smaller than many other major countries in the world. However, the people who live in the United States consume (or use up) a larger percentage of some natural resources, such as water. This means that the United States has a large “water footprint.”
According to the website , “People use lots of water for drinking, cooking, and washing, but even more for producing things such as food, paper, cotton clothes, etc. The water footprint is an indicator of water use that looks at both direct and indirect water use of a consumer or producer. The water footprint of an individual, community, or business is defined as the total volume of freshwater that is used to produce the goods and services consumed by the individual or community or produced by the business.”
The following table gives the population and water footprints of China, India, and the United States from 1997–2001.[16]
|Country |Population |Total Water Footprint* |
| |(in thousands) |(in 109 cubic meters per year) |
|China |1,257,521 |883.39 |
|India |1,007,369 |987.38 |
|United States |280,343 |696.01 |
(5) Notice that the countries are listed in the table above from highest to lowest population. Using the data on Total Water Footprint, rank the countries (from highest to lowest) according to their total water footprint.
(6) Rank the countries in order of water footprint per person (“per capita”) from highest to lowest. Be careful with the units on your numbers and final answer.
(7) How many times larger is the population of China compared with the population of the United States? Write your answer in a sentence. (You may want to refer back to Question 4.)
(8) Calculate how many times more water the average person in the United States uses compared to the average person in China.
(9) Write a sentence to explain the meaning of your answer to Question 8. (Remember the Writing Principle: Use specific and complete information.) Someone who reads what you wrote should understand what you are trying to say, even if they have not read the question or writing prompt.
Making Connections
Record the important mathematical ideas from the discussion.
Further Applications
(1) According to the data in this lesson, the per-person water footprint for the United States for
1997–2001 was 2,482.7 cubic meters per year per person.
(a) Write a sentence explaining what this number means.
(b) Find the current population of the United States. One good site is main/ www/popclock.html. Use this information and the given water footprint to estimate the current total water footprint of the United States.
(c) Look at the water footprint you calculated in Part (b). Does your answer seem reasonable given what you know about the size of water footprints?
(d) Now compare this number to the U.S. water footprint given in this lesson. How many times larger is it now?
Student Notes
Making Connections to the Lesson
(1) Which of the following was one of the main mathematical ideas of the lesson?
(i) Ratios are a way to compare measurements in different situations.
(ii) A water footprint measures the amount of water used by a person or group. This includes water used for cooking, drinking, cleaning, and to produce all the goods and services used by the person.
(iii) The number 311,000,000 can be written in scientific notation as 3.11 x 108.
(iv) A nation’s water footprint can be calculated by dividing the nation’s population by the amount of water used in that nation.
(2) In Lesson 1.6, you used scientific notation for large numbers. Understanding large numbers has been an important concept in previous lessons. Find specific examples from your previous OCEs in which you used the skills listed below. The lesson number is listed. You must give the number of the question.
In question number _________ in the OCE for Lesson 1.1, you identified the names of large numbers.
In question number _________ in the OCE for Lesson 1.2, you compared the sizes of large numbers.
Developing Skills and Understanding
(3) The website for the nonprofit organization Charity: Water[17] discusses the need for clean water around the world.
(a) The website states that worldwide, “90% of the 30,000 deaths that occur every week from unsafe water and unhygienic living conditions are of children under five years old.” The following statements are all correct interpretations of this statistic. Which gives the most complete information?
(i) 27,000 children die every week from unsafe water and unhygienic living conditions.
(ii) 27,000 out of the 30,000 deaths that occur every week from unsafe water and unhygienic living conditions are of children under five years old.
(iii) 90% of deaths from unsafe water and unhygienic living conditions are of children under five years old.
(iv) 90 out of 100 deaths that occur every week from unhealthy living conditions are of children under five years old.
(b) The website also states: “Almost a billion people on the planet don’t have access to clean drinking water.” If there are 6.9 x 109 people in the world, then approximately what percent of them live without clean drinking water? Round to the nearest tenth of a percent.
(4) According to data on the website for the Centers for Disease Control and Prevention (CDC)[18], 28% of adults were obese in 2010.
(a) According to the U.S. Census Bureau, about 63% of Americans are adults (18 and over). Use the U.S. population estimate of 311 million people to calculate the number of American adults in 2010. Round to the nearest ten thousand adults.
(b) According to the CDC, about how many of these adults were obese? Round to the nearest hundred thousand adults.
(c) What is this number in scientific notation?
(i) 5.49 x 107 adults
(ii) 5.49 x 106 adults
(iii) 0.549 x 107 adults
(iv) 54.9 x 106 adults
(v) 0.549 x 108 adults
Over the past several years, there has been a dramatic increase in obesity rates in the United States. Use the following website to answer the following questions about adult obesity in the United States:
(d) In 1995, approximately ___ out of 100 adults in the United States were obese. Round to the nearest adult.
(e) If there were 165 million American adults in 1995, about how many of them were obese? Round to the nearest million adults.
(f) About how many more American adults were obese in 2010 than in 1995?
(i) 2.3 x 107 adults
(ii) 2.9 x 107 adults
(iii) 4.1 x 107 adults
(iv) 2.3 x 108 adults
(v) 2.9 x 108 adults
Making Connections Across the Course
(5) Tannika has a health insurance plan that will reimburse her for 60% of her family’s health expenses after she pays a $2,000 deductible. A deductible is the amount a person pays (to a hospital, for example) before an insurance company will begin to pay for a percentage of the remaining expenses. Tannika has to pay the deductible and the percentage not covered by the insurance company. These are called “out-of-pocket expenses” because they are paid by the person who owns the policy.
Tannika records the total of her health care expenses in the spreadsheet below.
[pic]
(a) Which of the following formulas could Tannika use in Cell E1 to calculate the amount paid by her insurance?
(i) =0.6(B2 + B3 + B4 + B5) – 2000
(ii) =0.6 * B2 + B3 + B4 + B5 – 2000
(iii) =2000 − 0.6(B2 + B3 + B4 + B5)
(iv) =0.6(B2 + B3 + B4 + B5 – 2000)
(b) Which of the following formulas could Tannika use in Cell E2 to calculate her out-of-pocket expenses? There may be more than one correct answer.
(i) =0.4(B2 + B3 + B4 + B5 – 2000) + 2000
(ii) =0.4 * B2 + B3 + B4 + B5 + 2000
(iii) =2000 + 0.4(B2 + B3 + B4 + B5)
(iv) =(B2 + B3 + B4 + B5) – E1
Preparing for the Next Lesson (1.7)
(6) According to the order of operations, what is one correct way to solve this problem?
8 + 6 x (3 + 6) ÷ 2 – 4
(i) 8 + 6 x (3 + 6) ÷ 2 – 4
→ 8 + 6 x (3 + 6) ÷ 2
→ 8 + 6 x (3 + 3)
→ 8 + (18 + 3)
→ 8 + 21
→ 29
(ii) 8 + 6 x (3 + 6) ÷ 2 – 4
→ 8 + 6 x 9 ÷ 2 – 4
→ 8 + 54 ÷ 2 – 4
→ 8 + 27 – 4
→ 35 – 4
→ 31
(iii) 8 + 6 x (3 + 6) ÷ 2 – 4
→ 8 + (18 + 6) ÷ 2 – 4
→ 8 + (18 + 3) – 4
→ 8 + 21 – 4
→ 29 – 4
→ 25
(iv) 8 + 6 x (3 + 6) ÷ 2 – 4
→ 8 + 6 x (3 + 3) – 4
→ 8 + (18 + 3) – 4
→ 8 + 21 – 4
→ 29 – 4
→ 25
(v) 8 + 6 x (3 + 6) ÷ 2 – 4
→ 14 x (9) ÷ 2 – 4
→ 14 x (9) ÷ 2
→ (126) ÷ 2
→ (63)
→ 63
(7) Miguel has a coupon for 20% off any purchase in a furniture store. He decides to purchase a desk for $80. Excluding tax, how much does Miguel save on his purchase?
(i) $16
(ii) $40
(iii) $2
(iv) $4
(8) Sylvia is charged 8% tax for her $2 cheeseburger. How much does Sylvia owe the cashier?
(i) $2.08
(ii) $2.80
(iii) $2.16
(iv) $1.84
The following terms will be used in the next class. Make sure you understand what they mean.
Revenue: This is the amount of money that a business receives when it sells a product or service.
Net profit: The net profit is the actual amount of money a business makes after expenses. The expression for this is:
Net profit = Revenue − Expenses
For example, a restaurant might charge a customer $10 for a meal, but it cost the restaurant $4 for the food, $1 for the waiter’s paycheck, and $1 for the building. You need to add up all the restaurant’s expenses ($4 + $1 + $1 = $6). Then you subtract it from the total amount they make ($10) to figure out the net profit. The expression would be 10 – (4 + 1 + 1) = 4. The restaurant’s net profit is $4.
Net loss: A net loss is similar to net profit, but a business has a net loss if the net profit is a negative number.
For example, if the restaurant’s expenses were higher than the revenue, they would have a net loss. They could pay the waiter more ($5) and the building could cost more ($3). The expression would be
10 – (4 + 5 + 3) = −2. The restaurant’s net loss is $2.
(9) You will be expected to do the following things for the next class. Rate how confident you are on a scale of 1–5 (1 = not confident and 5 = very confident).
Before beginning Lesson 1.7, you should understand the concepts and demonstrate the skills listed below:
|Skill or Concept: I can … |Rating from 1 to 5 |
|Follow the order of operations. | |
|Find a percent of a number. | |
|Estimate 1% of a number. | |
(10) If your confidence ratings are below 3 for any of these skills/concepts, what are three things you might do to increase your confidence in these areas?
Specific Objectives
Students will understand that
• order of operations is needed to communicate mathematical expressions to others.
Students will be able to
• perform multistep calculations using information from a real-world source.
• rewrite multistep calculations as a single expression.
• explain the meaning of a calculation within a context.
Problem Situation: FICA Taxes
The United States government requires that businesses pay into two national insurance programs—Social Security and Medicare—which help senior citizens pay for their personal expenses and health care. Businesses take money out of their employees’ paychecks in order to pay the government. If you work for a business, your employer deducts Social Security and Medicare taxes from your paycheck. Also, the business pays a portion of the taxes for you. These taxes are called Federal Insurance Contributions Act (FICA) taxes.
People who own their own businesses are self-employed. They have to pay their own taxes. This
is called the self-employment tax. In this lesson, you will use a tax worksheet called the Short Schedule SE. This is an Internal Revenue Service (IRS) tax form. The IRS is the part of the government that collects taxes. It has many different types of forms for individuals and businesses to figure out how much they owe in taxes. With the Short Schedule SE, you will calculate how much two self-employed individuals owe in self-employment tax.
(1) Sundos Allianthi sells crafts such as jewelry and baskets for extra money. She does not have a farm or get any of the benefits on Line 1b. In 2010, she sold $11,385 in crafts and her expenses totaled $3,862. Expenses are the things she needed to buy for her business.
Fill out Section A—Short Schedule SE below for Sundos. How much self-employment tax does Sundos owe? Assume that Line 29 of her 1040 form has a 0 amount. This is asked for on Line 3 of the Short Schedule SE.
[pic]
(2) Raven Craig started a tutoring business at the end of 2010. She has no income to report on Line 1a or Line 1b of Schedule SE. She earned $1,050 and her expenses totaled $630. How much self-employment tax does Raven Craig owe?
[pic]
(3) In Question 1, you learned about Sundos Allianthi. You used the Short Schedule SE form to figure out how much self-employment tax she owes. Now, write your answer in a single expression that someone else could use and understand.
(4) Look back at the expression you wrote for Question 3. Imagine you have to explain the expression and how you calculated the tax to Sundos. Answer these questions about the expression:
(a) What does the operation $11,385 − $3,862 mean in the context? In other words, what does the result of this operation represent for Sundos?
(b) What does the operation of multiplying by 0.9235 mean in this context?
(c) What does the operation of multiplying by 0.153 mean in this context?
In 2010, the U.S. Congress passed the Tax Relief, Unemployment Insurance Reauthorization, and Job Creation Act of 2010. The act reduced the self-employment tax rate from 15.3% to 13.3%. This changes the amount in the first bullet under Line 5 of the Short Schedule SE.
(5) Predict how much Raven Craig and Sundos Allianthi will save in taxes in 2011 if their incomes and expenses are the same as they were in 2010. Do not use pencil and paper or a calculator. Write down your predictions of how much they will save.
Making Connections
Record the important mathematical ideas from the discussion.
Further Applications
(1) In Question 7c of the Lesson 1.7 assignment, you were asked to calculate the income tax for a person earning $63,500.
(a) Write a single expression for this calculation.
(b) The $4,750 in the third line of the table is based on information from the previous two lines. Explain how the $4,750 is calculated. (Hint: Start by thinking about where the $850 in Line 2 came from.)
Student Notes
Making Connections to the Lesson
(1) Which of the following was one of the main mathematical ideas of the lesson?
(i) In order of operations, you do operations in this order: 1) Within parentheses; 2) Exponents;
3) Multiplication; 4) Division; 5) Addition; 6) Subtraction.
(ii) Taxes are very complicated, and tax forms are hard to complete.
(iii) Part of quantitative reasoning is being able to read, interpret, and use quantitative information to perform a task.
(iv) It does not matter how you write your calculations as long as you get the correct answer.
(2) Refer back to Question 5 in Lesson 1.5 and Question 4 in this lesson (1.7). What important quantitative reasoning skill was used in both of these questions? Choose the best answer from the following.
(i) Both questions related to money.
(ii) Both questions related to making sense of numbers and calculations.
(iii) Both questions were about personal finance.
Developing Skills and Understanding
(3) Martin Binford is an author. He has no income he would report on line 1a or line 1b of his Schedule SE[19]. He earned $143,380 in 2010 from his books. He had $3,563 in expenses. How much self-employment tax does he owe?
[pic]
(4) Which of the following expressions can be used to compute how much self-employment tax Martin Binford owes?
(i) 0.029 + 0.9235($143,380 – $3,563) + $13,243.20
(ii) 0.029 x 0.9235 x $143,380 – $3563 + $13,243.20
(iii) 0.029(0.9235)($143,380 – $3563) + $13,243.20
(iv) 0.029(0.9235)($143,380 – $3563 + $13,243.20)
(5) The expression below shows another way to calculate Martin’s tax.
0.153(106,800) + 0.029(129,121.00 – 106,800)
Based on this expression, select the statement that describes how Martin’s income is taxed.
(i) Martin pays 15.59% tax on his income.
(ii) Martin pays 44.3% tax on his income.
(iii) Martin pays 15.3% in tax on the first $106,800 of his income. He pays 29% on his income over $106,800.
(iv) Martin pays 15.3% in tax on the first $106,800 of his income. He pays 2.9% on his income over $106,800.
(6) Miguel is moving and wants to estimate what his electricity bill will be in his new apartment. He looks at old bills and sees that he uses around 700 kWh of electricity each month. The utility company charges $6 each month plus 6.726 cents per kWh for the first 500 kWhs and 8.136 cents for each kilowatt-hour above 500.
(a) How much will Miguel pay for 700 kWh of electricity?
People often make a common error in situations like the one Question 6a. The purpose of the next two questions is to help you recognize this error and correct your work in part (a) if necessary.
(b) If someone bought three items for $1.50, 37 cents, and 5 cents, how much did they spend?
(c) Which of the following is most likely the common error in part (b)?
(i) Making an addition error such as 37 + 5 = 45 cents
(ii) Forgetting to change the cents to dollars: 1.50 + 37 + 5 = $43.50
(iii) Leaving off the decimal: 1.50 + 37 + 5 = $4,350
(7) Workers in the U.S. pay several types of taxes on income. The lesson discussed the FICA taxes. You also have to pay federal income tax. Your federal income tax rate is based on the amount of money you make. Income is broken into levels called tax brackets. The table below shows the tax brackets for 2011.[20]
|Taxable Income |Tax |
|$0–$8,500 |10% of taxable income |
|$8,500–$34,500 |$850 plus 15% of excess over $8,500 |
|$34,500–$83,600 |$4,750 plus 25% of excess over $34,500 |
|$83,600–$174,400 |$17,025 plus 28% of excess over $83,600 |
|$174,400–$379,150 |$42,449 plus 33% of excess over $174,400 |
|$379,150 plus |$110,016.50 plus 35% of excess over $379,150 |
(a) What tax rate does everyone pay on the first $8,500 of income?
(b) Calculate the income tax for a person earning $25,000.
(c) Calculate the income tax for a person earning $63,500.
(d) Refer to your answer for part (c). The total tax in part (c) is what percentage of the person’s income? Round to the nearest one percent.
Making Connections Across the Course
(8) In Lesson 1.6, it was determined that the water footprint for a typical American is
2,483 m3/year.
(a) A family of three would like to reduce their water footprint so that it is 75% of the typical American’s water footprint. Which calculation shows how they can estimate their target water footprint for one day? There may be more than one correct answer.
(i) (3 × 2,500 × [pic]) ÷ 365[pic]
(ii) 2,500 × 3 × 0.75
(iii) 3 × 2,500 × 0.75 ÷ 365
(iv) 2,500 × 3 × [pic]÷ 365
(v) 2,500 × 3 ÷ 0.75
(vi) 2,500 ÷ (365 × 0.75) × 3
(vii) 3 × (2,500 × 0.75) ÷ 365
(b) One thing a person can do to reduce his or her water footprint is to use less water every day. If each American were to reduce his or her daily water use by 2 m3 (2,642 gallons), how would you calculate the new annual water footprint for a typical American? There may be more than one correct answer.
(i) 2,483 − 2 × 365
(ii) (2,483 – 2) × 365
(iii) 2,483 – (2 × 365)
(iv) 2,483 × 365 – 2
(v) 2,483 – 365 × 2
(vi) (2,483 ÷ 365 – 2) × 365
(vii) 2,483 ÷ 365 – 2
(c) Which of the following would cause the greatest decrease in the American water footprint?
(i) Each American decreases his or her daily water footprint by 300 m3.
(ii) Each American decreases his or her daily water footprint to 95% of what it is now.
(iii) Each American decreases his or her annual water footprint by 120,000 m3.
(iv) Each American decreases his or her annual water footprint to 94% of what it is now.
Preparing for the Next Lesson (1.8)
(9) Which of the following represents 0.02%? There may be more than one correct answer.
(i) 2 out of 100
(ii) 0.2 out of 100
(iii) 0.02 out of 100
(iv) 2
(v) 0.02
(vi) 0.0002
(vii) 2 out of 1,000
(viii) 2 out of 10,000
(10) Which of the following is equivalent to 4%? There may be more than one correct answer.
(i) 0.04
(ii) 1/25
(iii) 4/100
(iv) 40/100
(v) 4 out of 100
(vi) 2 out of 5
(11) Which of the following is correct? There may be more than one correct answer.
(i) A percent is one part in every 100.
(ii) A percent can be converted into a decimal number by dividing that percent number by 100.
(iii) A percent can be converted into a decimal number by moving the decimal point two places to the left and removing the % sign.
(iv) 50% means 50 per 100 or 50/100 = 0.5.
(12) Which of the following is the percent estimate of 1/3, rounded to the nearest hundredth of a percent?
(i) 3.3%
(ii) 0.33%
(iii) 33.33%
(iv) 33.3%
(13) 1,352 is what percent of 40,929? Round to the nearest tenth of a percent.
(14) You will be expected to do the following things for the next class. Rate how confident you are on a scale of 1–5 (1 = not confident and 5 = very confident).
Before beginning Lesson 1.8, you should understand the concepts and demonstrate the skills listed below:
|Skill or Concept: I can … |Rating from 1 to 5 |
|Have a basic understanding of the word percent and the notation used to describe | |
|percentages (%). | |
|Use a calculator to divide two numbers and interpret the resulting decimal | |
|representation as a percent. | |
|Calculate and estimate percentages. | |
Self-Regulating Your Learning—The Work Phase
In an earlier lesson, you read in detail about what it means to effectively plan for your learning. That involved accounting for time and effort, your confidence (self-efficacy), study strategies, and learning goals. In this lesson, we will discuss the second phase of self-regulated learning (SRL), the work phase.
As the name implies, the work phase of SRL is where you are actually working on the problem or assignment. However, it is more than just getting the assignment done. In this phase, you monitor or pay attention to a variety of things. For example:
• What you are or are not understanding (and when).
• Which strategies you are using; which ones are working, and which ones are not.
• What emotions and feelings you are experiencing, both positive and negative.
• When you should seek help from others.
Let’s explore each of these in a little more detail.
Understanding: Self-regulated learners monitor what they understand and what they do not. This is done by frequently asking yourself: “Do I understand this?” or “Could I explain this to someone?” The goal is to monitor your understanding so that you may adapt your strategies, especially if you get stuck. Being honest about your understanding is important because it can help you progress successfully on a problem, or make you aware of your learning strengths and weaknesses. Sometimes, people talk about this as “thinking about your thinking.” Researchers call it metacognition.
Strategies: In learning about the SRL planning phase, you discovered that it can be useful to think about multiple strategies before you start working on a problem. In the work phase of SRL, having multiple strategies in mind (both those you have used before and those you have planned to try) can help when you get stuck. You can stop, think about how the problem is progressing, and try another strategy that you think might work. Self-regulated learners often make mental notes about which strategies work in which situations, and which ones are easiest to use. Evaluating strategies allows you to become better at solving a variety of problems.
Emotions: Self-regulated learners know how to monitor their emotions—especially negatives ones such as frustration or anger—so that these emotions do not cause them to give up on a problem. When they start feeling frustrated, self-regulated learners often do things such as trying new strategies, seeking help, or engaging in positive self-talk. This is saying things to yourself such as: “I know I can do this if I choose the right strategies and put in the effort, even if it is challenging.” The opposite is called negative self-talk, which involves saying things such as: “I am never going to get this! What is the point?” Monitoring and controlling your emotions, especially the negative ones, can be challenging and may require a lot of practice, but the benefits are worth it.
Seeking Help: With practice and experience, self-regulated learners know when it is beneficial to stop working and find someone else with whom they can discuss the problem. There is nothing wrong with getting help when you are learning something new. Some people think that asking for help means you do not have ability, but the truth is that knowing when to seek help is part of being an effective learner. Seeking help can save you time because you avoid the added frustration of making a lot of effort without making any progress. If you are spending a lot of time on a problem, you have tried several strategies without success, or you are not able to control negative emotions, stop and write down your questions. Bring the written questions with you and discuss the problem with someone else as soon as you can. Help could come from your instructor during his or her office hours, a campus learning center, or other classmates.
During the work phase, you are required to juggle two things at once: (1) Working on the problem or assignment and (2) monitoring your progress (e.g., thinking about your thinking). This process takes practice, however, it is important to master if you want to become a self-regulated learner. Thinking about how you are working makes the work easier and gives you information for the SRL reflect phase. You will explore the reflect phase in an upcoming lesson. Until then, practice these work strategies while you are working on problems and class assignments.
Specific Objectives
Students will understand that
• percents involve a numerator (comparison value) and a denominator (reference value).
Students will be able to
• correctly identify the quantities involved in a verbal statement about percents.
• convert between ratios and percents.
• convert between the decimal representation of a number and a percent.
• read and use information presented in a two-way table.
Problem Situation: The Language of Percentages
The World Health Organization () is the part of the United Nations that oversees health issues in the world. The WHO leads numerous studies on tobacco use around the world. In its study on Gender and Tobacco, the organization learned that tobacco use among women is increasing. For example, recent research shows that just as many young girls smoke as young boys. The report is filled with information about percentages of women who smoke, percentages of men who smoke, and the percentage of smokers who start smoking by age 10. The language used to describe this information
can be difficult to understand. Pay close attention to the language used to describe a percent at the beginning of this lesson. This will help you to understand new findings in the relationship between tobacco use and gender.[21]
Consider the following two quantities:
• Quantity 1 (Q1): The percentage of women who smoke.
• Quantity 2 (Q2): The percentage of smokers who are women.
(1) Are these two quantities equal (Q1 = Q2)? Could Q1 be greater than Q2 (Q1 > Q2)? Could Q1 be less than Q2 (Q1 < Q2)? Be prepared to explain your reasoning.
(2) What information would you need to compute these percentages?
Questions 3 and 4 present two situations with data. You can use these situations to test your ideas from Questions 1 and 2.
(3) Suppose a study on smoking was conducted at Midland University. The following table indicates the results of the study.
| |Men |Women |
|Smokers |4,572 |5,362 |
|Nonsmokers |10,284 |12,736 |
(a) What percentage of women smoke at Midland University?
(b) What percentage of smokers at Midland University are women?
(4) Suppose a study was conducted at Northwest College. The following table indicates the results of the study:
| |Men |Women |
|Smokers |1,256 |536 |
|Nonsmokers |1,028 |1,053 |
(a) What percentage of women smoke at Northwest College?
(b) What percentage of smokers at Northwest College are women?
(c) A newspaper stated that 40% of the male students at Northwest College smoked. Is that claim reasonable? Explain why or why not.
(5) In 2006, the World Health Organization conducted a study about smoking in the United States and China. The organization reports that 3.7% of the adult women in China smoke tobacco products. In the United States, 19% of adult women smoke.
(a) Out of 100 adult women in China, about how many are smokers?
(b) Out of 1,000 adult women in China, about how many are smokers?
(c) Out of 100 adult women in the United States, about how many are smokers?
(d) Out of 1,000 adult women in the United States, about how many are smokers?
(e) Are there more women smokers in China or the United States?
(f) Suppose you read that 590 out of 1,000 men in China smoke. Based on these data, what percentage of men in China smoke?
Making Connections
Record the important mathematical ideas from the discussion.
Further Applications
The following question is included in the out-of-class experience for this lesson. Write an explanation for your answers to Parts (a) and (b).
(1) A teacher has collected data on the grades his students received in his two classes. The following tables show two different ways to represent the same data.
Table 1
| |Grades |
| |A |B |C |D |F |
|Morning Class |12.5% |25.0% |37.5% |6.3% |18.8% |
|Afternoon Class |14.3% |20.0% |37.1% |8.6% |20.0% |
Table 2
| |Grades |
| |A |B |C |D |F |
|Morning Class |44.4% |53.3% |48.0% |40.0% |46.2% |
|Afternoon Class |55.6% |46.7% |52.0% |60.0% |53.8% |
(a) Which table could be used to answer the following question: “What percentage of the students who received an A are in the morning class?”
(b) Which table could be used to answer the following question: “What percentage of the students in the morning class received an A?”
Student Notes
Making Connections to the Lesson
(1) Which of the following was one of the main mathematical ideas of the lesson?
(i) A percentage is calculated by dividing one number by another number.
(ii) Smoking is a major health problem in the United States and China.
(iii) A percentage is a comparison of two numbers. To understand the meaning of a percentage, it is important to know what two quantities are being compared.
(iv) The percentage of students who are parents is the same as the percentage of parents who are students.
(2) You have worked with percentages in Lessons 1.3, 1.5, 1.6, and 1.7. Select one or two examples that helped you understand percentages from one of these lessons. Write a short explanation of how they helped further your understanding.
Developing Skills and Understanding
(3) Data from the National Postsecondary Student Aid Study (NPSAS)[22] provides a statistical snapshot of the proportion of community college students who majored in different fields of study in 2003–04. A total of 25,000 community college students were included in the study. Table 1 displays the total number of community college students who majored in each of the following fields of study in 2003–04.
Table 1
|Field of Study |Number of Students who Majored in |Percentage of Students who Majored in |
| |Field |Field |
|Humanities |3,700 | |
|Social/Behavioral Sciences |1,250 | |
|Mathematics and Science |900 | |
|Computer/Information Science |1,525 | |
|Engineering |1,025 | |
|Education |2,025 | |
|Business/Management |4,600 | |
|Health |5,975 | |
|Vocational/Technical |1,225 | |
|Other Technical/Professional |2,775 | |
(a) Complete the table by filling in the percent of community college students who majored in each field of study. Round to the nearest one percent.
(b) What was the most popular major in 2003–04?
(i) Humanities
(ii) Business/Management
(iii) Health
(iv) Education
(c) Fill in the blanks to complete the following statements.
About _______ out of every 100 community college students in 2003–04 majored in the most popular field.
About ________ out of every 1,000 community college students in 2003–04 majored in the most popular field.
(4) Select the answers that correctly complete the statement from the list below: A New York Times story[23] reported that 10% of male high school dropouts are in jail or detention centers. According to this statistic, about ________ in every ________ male high school dropouts is (are) in jail or juvenile detention. There may be more than one correct answer.
(i) 1 in every 10
(ii) 10 in every 100
(iii) 1 in every 10%
(iv) 1 in every 100
(v) 0.1 in every 100
(5) A teacher has collected data on the grades his students received in his two classes. The tables below show two different ways to represent the same data as percentages.
Table 2
|Grades |A |B |C |D |F |
|Morning Class |12.5% |25.0% |37.5% |6.3% |18.8% |
|Afternoon Class |14.3% |20.0% |37.1% |8.6% |20.0% |
Table 3
|Grades |A |B |C |D |F |
|Morning Class |44.4% |53.3% |48.0% |40.0% |46.2% |
|Afternoon Class |55.6% |46.7% |52.0% |60.0% |53.8% |
(a) Which table could be used to find out what percentage of the students who received an A are in the morning class?
(b) Which table could be used to find out what percentage of the students in the morning class received an A?
(c) What are the reference values in Table 2?
(i) The number of students in a certain class.
(ii) The number of students who got a certain grade.
(iii) The number of students in a certain class who got a certain grade.
(iv) The total number of students in both classes.
(d) What are the reference values in Table 3?
(i) The number of students in a certain class.
(ii) The number of students who got a certain grade.
(iii) The number of students in a certain class who got a certain grade.
(iv) The total number of students in both classes.
Making Connections Across the Course
(6) What are the four things you should monitor when you are self-regulating your learning during the work phase? Try to think of all four aspects when you solve Question 7.
(7) Congratulations! You won a lottery prize and have a taxable income of $1,025,400. Use the table below to answer the following questions.
|Taxable Income |Tax |
|$0−$8,500 |10% of taxable income |
|$8,500−$34,500 |$850 plus 15% of excess over $8,500 |
|$34,500−$83,600 |$4,750 plus 25% of excess over $34,500 |
|$83,600−$174,400 |$17,025 plus 28% of excess over $83,600 |
|$174,400−$379,150 |$42,449 plus 33% of excess over $174,400 |
|$379,150 plus |$110,016.50 plus 35% of excess over $379,150 |
(a) How much tax will you pay on your winnings?
(b) Which of the following expressions can be used to calculate the tax?
(i) $1,025,400 – 0.35($379,150 – $110,016.50)
(ii) 0.35 + $379,150($1,025,400 – $110,016.50)
(iii) ($1,025,400 + $110,016.50) – ($37,650 × 0.35)
(iv) $110,016.50 + 0.35($1,025,400 – $379,150)
(v) $1,025,400 – 0.35($1,025,400 – $379,150)
(8) The work phase of regulating your learning includes checking your understanding. One of the ways to do this is by asking yourself: “Can I explain this to someone?” Check your understanding by explaining your answer to Question 7b.
Preparing for the Next Lesson (1.9)
According to the World Health Organization (WHO), “Every person is at risk of foodborne illnesses.”[24] A foodborne illness is an illness that a person gets from eating food that has spoiled or been contaminated in some way.
(9) In industrialized countries, such as the United States, up to 30% of the population suffers from foodborne diseases each year. This means that 30 out of _________ people living in industrialized countries will likely suffer from foodborne diseases each year.
(10) In 1994, an outbreak of illness due to ice cream contaminated with the bacteria salmonella occurred in the U.S. The outbreak affected an estimated 224,000 people.
(a) If the total population in the United States at that time was 260,000,000, which is the best estimate for the percentage of people who were affected?
(i) About 0.1%
(ii) About 1%
(iii) About 5%
(iv) About 10%
(v) About 25%
(b) Complete the following statement: Approximately 86 out of every _______ people in the United States were affected by the 1994 salmonella outbreak.
(11) A report about foodborne illnesses indicated, “About 1 egg out of every 20,000 contains salmonella inside the shell.” This means that
(i) 0.005% of eggs contain salmonella.
(ii) about 1% of eggs contain salmonella.
(iii) more than 1% of eggs contain salmonella.
(iv) approximately 50 out of every 100,000 eggs contain salmonella.
(12) In 2011, Germany had an outbreak of illness caused by the bacteria called e. coli. As of June 15 of that year, 3,235 people in Germany had become sick and 36 had died.[25] What percentage of those who got sick also died? Round to the nearest tenth of percent.
(13) You will be expected to do the following things for the next class. Rate how confident you are on a scale of 1–5 (1 = not confident and 5 = very confident).
Before beginning Lesson 1.9, you should understand the concepts and demonstrate the skills listed below:
|Skill or Concept: I can … |Rating from 1 to 5 |
|Have a basic understanding of the word percent and the notation used to describe | |
|percents (%). | |
|Use a calculator to divide two numbers and interpret the resulting decimal | |
|representation as a percent. | |
|Calculate percentages. | |
Specific Objectives
Students will understand that
• a percent has different uses, including being used to express the likelihood (or probability) of a certain event.
• the importance of selecting the correct comparison value and reference value in calculating percentages.
Students will be able to
• extract relevant information from a table.
• select the appropriate values to calculate probabilities.
Problem Situation: Using Percentages to Describe the Accuracy of Medical Tests
Some athletes use performance-enhancing drugs (PEDs) to improve how they do in sports. Schools, sports leagues, and other sports organizations usually do not allow the use of PEDs. These groups can administer or give athletes a blood or urine test to determine if the athletes are using drugs.
In this situation, 500 athletes have undergone a test to determine if they use PEDs. A positive (+) test result indicates or shows that the athlete is using a PED. A negative (–) test result indicates the athlete is not using these drugs. However, this test is not 100% accurate. This means that some errors may have occurred in the test results. The table below shows how often the test correctly determined if athletes used PEDs.
| |Athletes Using PEDs |Athletes Not Using |Total |
| | |PEDs | |
|Positive test result |9 |5 | |
|Negative test result |1 |485 |486 |
|Total |10 | |500 |
Use the figures or numbers in the table to answer the questions below. You will use the figures in the table to decide on the probability that this test gives correct and incorrect results. Probability means the chance that something happens. Report probabilities in percents (%). Be careful what figures you use for the numerator and denominator in your calculations.
(1) The table is missing one row total and one column total. Fill in the missing totals.
(2) Correctly identify the presence of PEDs using the steps below.
(a) How many athletes are using PEDs?
(b) How many of the athletes using PEDs received a positive test result?
(c) If an athlete is using PEDs, what is the chance this test gives a positive result?
(3) Correctly identify the absence of PEDs using the steps below.
(a) How many athletes are not using PEDs?
(b) How many of the athletes not using PEDs received a negative test result?
(c) If an athlete is not using PEDs, what is the chance that this test gives a negative result?
(4) False Negatives: Did you see how one athlete using PEDs received a negative test result? This means the test incorrectly identified this single athlete. This is called a false-negative test result.
Think about this situation: An athlete gets a negative result on a test. What is the chance the result is a false negative? Hint: Think about the ratio of incorrect negative results compared to all negative results.
(5) False Positives: The test also produced false positives. This means the test gave some athletes not using PEDs positive results.
Think about a situation in which a school principal finds that an athlete gets a positive result on the test. Answer these questions:
(a) What is the chance the result is a false positive?
(b) How should the principal think about this percentage? What should the principal do with this information?
(6) You can use different percentages to show how accurate the test was. A test is accurate when it produces very few mistakes or errors. Pick one figure or percentage that you think best describes how accurate the test was. Explain what this figure says about the test and why you picked this figure.
(7) Now, think about how to use a figure or percentage to show how inaccurate the test was. A test is inaccurate if it produces many errors. Pick one figure to show how inaccurate the test was. Explain what this figure says about the test and why you picked this figure.
Making Connections
Record the important mathematical ideas from the discussion.
Further Applications
(1) Refer to the problem situation used in this lesson and to Question 5 in the OCE for this lesson. You will call the population used in the lesson P1 and the population used in OCE Question 5 P2.
(a) A prevalence rate is the percentage of people in a population who have a certain disease or behave in a certain way. Find the prevalence rate of using PEDs for P1 and P2. Another way to say this is, “What percent of the population used PEDs?” Put your answers in the following table.
| |P1 |P2 |
|Prevalence rate | | |
|True positive rate | | |
|False Positive rate | | |
(b) Complete the table with the true positives (the percentage that were correctly identified as using PEDs) and false positive rates for each population. You already have that information in your lesson and OCE work.
(c) Based on the information in the table, what appears to affect the rate of false positives? Write your answer using the Writing Principle.
Student Notes
Making Connections to the Lesson
(1) Which of the following was one of the main mathematical ideas of the lesson?
(i) A probability is a percentage in which the chance of an event is measured as a ratio out of 100.
(ii) Medical tests are far less accurate than most people think.
(iii) To calculate a percentage, divide the comparison value by the reference value.
(iv) Probabilities are not related to percentages.
(2) In the problem situation in Lesson 1.9, there was a 90% chance that an athlete who used Performance Enhancing Drugs (PEDs) would have a positive test result. You could explain this by saying 90 out every 100 athletes who use PEDs will have a positive test result.
Refer to previous lessons. Find two lessons that use percentages. Choose one question using a percentage from each lesson. In the table below, list the lesson and the question number then write an interpretation of the percentage similar to the example above. Suggested lessons: 1.3, 1.5, 1.7, and 1.8.
|Lesson |Question Number |Interpretation of the percentage |
| | | |
| | | |
| | | |
| | | |
| | | |
| | | |
Developing Skills and Understanding
(3) About 16% of drivers are uninsured. There were approximately 196 million drivers in the United States in 2003.[26] How many of these drivers were likely uninsured?
(i) 31,360
(ii) 31,360,000
(iii) 313,600,000
(iv) 3,136,000,000
(4) Determine whether each of the following is an example of a false negative or an example of a false positive.
(a) A woman has breast cancer. Her test indicates that she does not have breast cancer. This is an example of …
(i) A false negative
(ii) A false positive
(iii) A true positive
(b) A woman does not have breast cancer. Her test indicates that she does have breast cancer. This is an example of …
(i) A false negative
(ii) A false positive
(iii) An accurate result
(5) A test is administered to 500 athletes to determine if they are using performance-enhancing drugs (PEDs). A positive test result indicates that the athlete is using performance-enhancing drugs; a negative test result indicates that the athlete is not using these drugs. However, this test is not 100% accurate, so some errors occur. The following table shows the test results for a group of athletes.
| |Athletes using PEDs |Athletes not using PEDs |TOTAL |
|Positive test result |90 |4 |94 |
|Negative test result |10 |396 |406 |
|TOTAL |100 |400 |500 |
Use the information in the table to answer the following questions.
(a) How many athletes are using PEDs?
(b) How many of these received a positive test result?
(c) If an athlete is using PEDs, which of the following describes the chance that this test will return a positive result? There may be more than one correct answer.
(i) 90 out of 100 chance of receiving a positive test result if one is using PEDs.
(ii) 90% chance of receiving a positive test result if one is using PEDs.
(iii) 9% chance of receiving a positive test result if one is using PEDs.
(d) What is the chance that a positive test result is a false positive? Round to the nearest tenth of the percent.
(e) If an athlete is not using PEDs, what is the chance that this test will return a negative result?
(i) 99% chance of receiving a negative test result if one is not using PEDs.
(ii) 4 out of 400 chance of receiving a negative test result if one is not using PEDs.
(iii) 39.6% chance of receiving a negative test result if one is not using PEDs.
(f) What is the chance that a negative test result is a false negative? Round to the nearest tenth of a percent.
(6) A hospital tracks the number of cases that come into its Emergency Room during each eight-hour shift. The cases are listed in categories based on the severity of the illness or injury. The categories from least severe to most severe are: stable, serious, and critical. The following table gives the data for a week.
(a) Complete the missing blanks in the table.
| |Stable |Serious |Critical |Total |
|8:00 am–3:59 pm |250 |120 |45 |415 |
|4:00 pm–11:59 pm |270 |230 |105 | |
|12:00 am–7:59 am | |175 |95 |460 |
|Total |710 | |245 |1480 |
A nursing supervisor ranks the shifts based on two different criteria.
(b) Which shift received the highest percentage of the total critical cases? Rank the shifts from highest to lowest. Round to the nearest one percent.
|Shift |Percentage of Total Critical Cases |
| | |
| | |
| | |
(c) Which shift has the highest ratio of critical cases compared to the shift’s total cases?
|Shift |Percentage of Total Cases in Shift |
| | |
| | |
| | |
(d) The hospital schedules nursing staff based on the number and severity of expected cases. One goal of scheduling is that more experienced nurses should work on critical cases. The nursing supervisor considers the overall number of experienced nurses and the ratio of experienced nurses to the less experienced nurses. Based on these data, which of the following conclusions could be drawn?
(i) The highest number and the highest ratio of experienced nurses should be scheduled during the 12:00 am–7:59 am shift.
(ii) The highest number and the highest ratio of experienced nurses should be scheduled during the 4:00 pm–11:59 pm shift.
(iii) The highest number of experienced nurses should be scheduled during the 4:00 pm–11:59 pm shift. The highest ratio of experienced nurses should be scheduled during the 12:00 am–7:59 am shift.
Making Connections Across the Course
(7) We can save time and work by using spreadsheets to perform calculations. To do this, you use formulas as you saw in your OCE for Lesson 1.4. The spreadsheet below could be used to calculate the self-employment taxes from Lesson 1.7.
[pic]
(a) You are going to set up a spreadsheet to calculate Sundos Allianthi’s self-employment tax. Use the information given in Lesson 1.7 to fill in the blanks for in cells B2–B5.
|B2: |B3: |B4: |B5: |
(b) Create an actual spreadsheet like the one shown above. Enter the information from Part (a).
(c) Write a formula for cell B7 that will calculate the self-employment tax. Remember to start the formula with an “=” sign. In a spreadsheet, you use an asterisk ( * ) to indicate multiplication. So B3 times B4 would be written as B3*B4. Record your formula below. (Note: You can check if your formula is correct by comparing the result of the calculation with your work in the lesson.)
(d) Suppose Sundos made a mistake in calculating her expenses. The expenses should be $4,371. Enter this new value into the spreadsheet. What is the new amount for the self-employment tax?
(e) Why did the spreadsheet specify that the entries for B4 and B5 be written as decimals? Select the best explanation.
(i) Percentages are easier to work with when written in decimal form because the numbers are smaller.
(ii) It is a rule that you always move the decimal two places to the left with a percentage.
(iii) The spreadsheet uses the number in the cell for the formula. The percentages had to be written as decimals so they could be used in the calculation.
(iv) It did not matter that the spreadsheet asked for decimals. The percentages could have been entered without the change. Nothing would have changed in the spreadsheet because percentages are equivalent to the decimal.
Self-Regulating Your Learning: The Reflect Phase
The last phase in regulating your learning is the reflect phase. In this phase, after you finish a problem
or assignment, you intentionally reflect on how your learning and problem solving went. You gather information about yourself, about studying, and about learning in general. This information is then used to improve future learning situations. Here are some things that self-regulated learners reflect upon:
• Confidence (self-efficacy)
• Strategy selection
• Time and effort
• Emotions
• Causes of success and setbacks
Confidence (Self-Efficacy): Regulating your learning means that you continuously pay attention to how much you believe that you can succeed at what you are trying accomplish. This is important after you complete a problem because it allows you to plan for what you will need as you move forward. If you rate your confidence low, then you would benefit from spending more time practicing and studying, and you may decide to get additional help. If you do not stop to think about how things went, it is easy to just move on to the next concept, thinking that you understand something you do not. Also, it is important to give yourself credit for your successes. You will feel better about spending the time and effort and you will be more motivated to continue working hard.
Strategy Selection: When regulating your learning, look back at the strategies you used when working on a problem or assignment. Make note of what seemed to work well for certain problems and what strategies seemed easier. This information will guide your plan phase in preparing for a new assignment. You can practice this by asking yourself: “What worked well and what did not?”
Time and Effort: Pay attention to the time and effort it took to complete an assignment. Reflect on whether you planned accurately. When doing this, try to identify the types of things you may need more time for in the future, or what might be more of a challenge. This information will be used during the plan phase.
Emotions: For successful learning, it is important to manage your emotions, especially your frustration and anxiety. One way to do this is to ask yourself what caused you to become frustrated or anxious and think about what helped you overcome those feelings. This gives you tools to deal with those feelings when they come up again.
Causes of Success and Failure: One of the most common challenges for students is correctly identifying the reasons for both their successes and their setbacks. Students often blame external factors for shortcomings. When faced with challenges, students often blame the teacher (“She does not explain well”); or maybe the book (“It is hard to read and it is confusing”); or the test itself (“It was full of trick questions.”) The problem with blaming external factors is that it gives you little control over your own learning outcomes. On the other hand, by considering internal factors—ones you can control—then you are in charge of your learning outcomes. For example, when facing a setback, ask yourself:
• “Did I spend enough time on this assignment?”
• “Did I use the right strategies?”
• “Did I seek help when I needed it?”
• “Did I put in the work and effort that was really required?”
These types of self-reflection questions help you understand yourself better and assist you in becoming a more effective learner.
Preparing for the Next Lesson (2.1)
(8) The Medical Center in Houston, Texas, is bound by US-59 to the north, I-610 to the west (west loop),
I-610 to the south (south loop), and Hwy 288 to the east. The region is roughly a 3-mile by 4-mile rectangle.
(a) What is the area of the Medical Center?
(b) What are the correct units for the area? There may be more than one correct answer.
(i) miles
(ii) square miles
(iii) mi2
(9) Which of the following represent(s) the number 8.4 billion? There may be more than one correct answer.
(i) 840,000,000,000
(ii) 8,400,000,000
(iii) 8.4 x 109
(iv) 8.4 x 1010
(v) 8,400 million
(10) Certain words and phrases indicate that division is required to compute an answer. For example, per, ratio, and divide into indicate division. There are also different symbols for division—including ÷ and the fraction bar (/). Which of the following does not indicate division?
(i) To compare gasoline usage, compute miles per gallon.
(ii) Convert 1/4 to a decimal.
(iii) To compute a bill, total all charges.
(iv) To compute how fast water flows past a meter, compute gallons per minute.
(v) To compute how to share tips among five waiters, compute dollars per person.
(11) You drive 310 miles on 15 gallons of gas. Select the statement(s) that correctly summarize(s) the situation. There may be more than one correct answer.
(i) Your gas mileage is about 15 miles per gallon.
(ii) Your gas mileage is about 20 miles per gallon.
(iii) You can drive a little more than 15 miles on a gallon of gas.
(iv) You can drive a little more than 20 miles on a gallon of gas.
(12) You will be expected to do the following things for the next class. Rate how confident you are on a scale of 1–5 (1 = not confident and 5 = very confident).
Before beginning Lesson 2.1, you should understand the concepts and demonstrate the skills listed below:
|Skill or Concept: I can … |Rating from 1 to 5 |
|Understand the concept of area. | |
|Comprehend numbers up to the billions place. | |
|Use a calculator to divide numbers. | |
|Interpret fractions as division. | |
|Interpret a decimal number. | |
During any class, it is important to frequently and accurately assess what you do and do not know. This is especially true before a quiz or test or when ending a module or chapter.
Math is different from many subjects. In math, you often have to show you can complete a problem, not just remember facts or choose the right answer. Every math student has had the experience of looking at work they have previously completed or examples done in the book and thinking, “I know how to do that,” only to get home or into a test and not be able to do a similar problem.
To check your understanding accurately, you must do problems that represent the concepts and skills you need to know. If you take time to accurately assess what you know, you can cut down on your study time. You can dedicate your study time to learning only the concepts and skills you need to understand better.
Assessing Your Understanding
The table on the following page lists the Module 1 concepts and skills you should understand. This exercise helps you assess what you understand. After completing it, you will be able to prioritize your review time more effectively.
1. Assess your understanding.
• Go through the topics list and locate each concept or skill in the Module 1 in-class or OCE materials.
• If you have not used the skill in a while, do two or more problems to check your understanding.
• If you have recently used the skill and feel confident that you did it correctly, rate your understanding a 4 or 5.
• If you remember the topic but could use more practice, rate your understanding a 3.
• If you cannot remember that skill or concept, rate your understanding a 1 or 2.
Now that you have done an initial rating of your understanding, it is time to begin reviewing. Complete the remaining steps. The goal is to have a confidence rating of 4 or 5 on all the topics in the table when you have finished your review of Module 1.
2. Start at the beginning of module and reread the material in the lessons, the OCE, and your notes on the skills and concepts you rated 3 or below.
3. Select a few problems to do. Do not look at the answer or your previous work to help you.
4. Once you have finished the problems, check your answers. If you are not sure if you have done the problems correctly, check with your instructor, other classmates, and your previous work or work with a tutor in the learning center.
5. Rate your confidence on this skill again. If you understand the concept better, rate yourself higher. Begin a list of topics that you want to review more thoroughly.
6. If you have time, do one or two problems on skills or concepts you rated 4 or above.
7. For topics that you need to review more thoroughly, make a plan for getting additional assistance by studying with classmates, visiting your instructor during office hours, working with a tutor in the learning center, or looking up additional information on the Internet.
|Module 1 Concept or Skill |Rating |
|Working with and Understanding Large Numbers |
|Place value and naming large numbers (1.1) | |
|Scientific notation (1.6) | |
|Calculations with large numbers (1.6) | |
|Relative magnitude and comparison of numbers (1.6) | |
|Estimation and Calculation |
|Rounding (1.1) | |
|Fractions and decimals (1.3) | |
|Relationship of multiplication and division (1.4) | |
|Order of operations (1.4) | |
|Properties that allow flexibility in calculations: Distributive Property, Commutative Property (1.4) | |
|Perform multistep calculations (1.7) | |
|Percentages and Ratios |
|Estimations with fraction and percent benchmarks (1.2, 1.3) | |
|Calculate percentages (1.3) | |
|Write and understand ratios (1.6) | |
|Calculate percentages from a two-way table (1.8, 1.9) | |
|Use percentages as probabilities and ratios (1.9) | |
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This lesson is part of QUANTWAY™, A Pathway Through College-Level Quantitative Reasoning, which is a product of a Carnegie Networked Improvement Community that seeks to advance student success. The original version of this work, version 1.0, was created by The Charles A. Dana Center at The University of Texas at Austin under sponsorship of the Carnegie Foundation for the Advancement of Teaching. This version and all subsequent versions, result from the continuous improvement efforts of the Carnegie Networked Improvement Community. The network brings together community college faculty and staff, designers, researchers and developers. It is a research and development community that seeks to harvest the wisdom of its diverse participants through systematic and disciplined inquiry to improve developmental mathematics instruction. For more information on the QuantwayTM Networked Improvement Community, please visit .
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Quantway™ is a trademark of the Carnegie Foundation for the Advancement of Teaching. It may be retained on any identical copies of this Work to indicate its origin. If you make any changes in the Work, as permitted under the license [CC BY NC], you must remove the service mark, while retaining the acknowledgment of origin and authorship. Any use of Carnegie’s trademarks or service marks other than on identical copies of this Work requires the prior written consent of the Carnegie Foundation.
This work is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported License. (CC BY-NC)
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[1]Best, J. (2001). Damned lies and statistics. University of California Press: Berkeley and Los Angeles.
[2]Best, J. (2001). Damned lies and statistics. University of California Press: Berkeley and Los Angeles.
[3]Retrieved from .
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[6] Retrieved from U.S. Census Bureau, ipc/www/worldhis.html.
[7]Retrieved from .
[8] Retrieved from graphics/how-the-average-consumer-spends-their-paycheck.
[9]Retrieved from westwood.edu/resources/student-budget
[10]Retrieved from credit-card-debt-statistics.html
[11]Retrieved from Financial-Planning/Debt-Consolidation/Credit-Card-Debt-Statistics
[12]Retrieved from msnbc.id/35185920/ns/us_news-life/t/coast-to-coast-double-digit-college-tuition-hikes
[13]Retrieved from movies/records/budgets.php.
[14]Retrieved from Rajan, A. Forget carbon: you should be checking your water footprint. Monday, 21 April 2008. Link []
[15]Retrieved from
[16]Retrieved from
[17]
[18]
[19]Retrieved from
[20]
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LESSON 1.1
Every year since 1950, the number of American children gunned down has doubled.
OCE 1.1
LESSON 1.2
OCE 1.2
LESSON 1.3
OCE 1.3
LESSON 1.4
OCE 1.4
LESSON 1.5
OCE 1.5
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xy
xy
1
0
8
^
8
^
0
1
LESSON 1.6
OCE 1.6
LESSON 1.7
OCE 1.7
LESSON 1.8
OCE 1.8
LESSON 1.9
OCE 1.9
REVIEW
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