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Name________________________Date_______________7.RP.3 Class ____________Percent ErrorKey Takeaways:Standard: Use proportional relationships to solve multistep ratio and percent problems. Examples: simple interest, tax, markups and markdowns, gratuities and commissions, fees, percent increase and decrease, percent error.Percent error expresses the error of an estimate or measurement as a percentage of the correct amount. It compares the error to the correct amount. Percent error is useful because it allows us to compare errors in scenarios that have different actual amounts.Vocabulary: actual, measured___________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________Activate Prior Knowledge!Breanna Stewart and Steph Curry are on a basketball court. Curry stands next to a hoop and shoots, missing the hoop by 6 inches. Stewart shoots at the same hoop, but while standing at the opposite end of the court. She also misses the hoop by 6 inches.Would you describe these two missed shots as equally bad? Why or why not?Guided Practice1. Kayla is filling up a bath tub. She estimated that the bath tub had a volume of 60 gallons, but it actually held 50 gallons of water.(a) How far off was Kayla’s estimate?(b) Calculate Kayla’s error as a percentage of the correct volume of the bathtub.2. Lebron James guessed that he could make 400 three-point shots during a practice. However, he was only able to make 320. Carmelo Anthony guessed that he could make 200 threes in a practice, but he was only able to make 120. Which person had a lesser percent error?Independent Practice: Mild 508508053530500Mr. Adams keeps a large jar of jelly beans in his classroom. The student who guesses closest to the actual amount will win the whole jar! Rahjon guesses 57 jelly beans. It turns out there are 50 jelly beans in the jar.Part A: How far off was Rahjon’s guess?Answer: __________Part B: What is Rahjon’s percent error?a. 7%b. 12%c. 14%d. 86%The planner of the school carnival estimated that they will sell 500 hot dogs. They only sell 400. What is the percent error of the estimate?20%25%80%100%Ms. Fischler was planning her wedding. She estimated that 260 guests will come, but 325 guests showed up. What is her percent error?a. 20%b. 25%c. 65%d. 80%Albin made a mistake when measuring the volume of a fish tank. He found the volume to be 65 liters; however the real value for the volume is 50 liters. What is the percent error?a. 15%b. 23%c. 30%d. 70%Independent Practice: Medium An appliance company is testing ovens to make sure they heat to the correct temperature. The test requires an oven that is set to 350°F to be no more than 2.5% off of that temperature; ovens that have more error than 2.5% are rejected.What is the lowest temperature than an oven could show on the test without being rejected?Michael and Matthew are playing a game where they guess they must guess the correct height of various items. Michael says that Matthew is 6 feet tall. Matthew’s actual height is 5 feet. Matthew guesses that the school building is 499 feet tall when it is really 500 feet tall. (a) Can you determine which student would have a lesser percent error without calculating the actual percents? Explain how.___________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________(b) Calculate the percent error for each student to confirm your answer.A construction worker measured a wall as 14 feet wide by 20 feet tall. According to the blueprint, the actual dimensions were 14 ? feet by 18 feet tall. What is his percent error in finding the area of the wall, rounded to the nearest percent?The director of the NYC Road Runners club miscalculates by 1 cm when measuring the distance for the marathon. A surgeon miscalculates by 1 cm when performing open heart surgery. Who has the greater percent error? Explain how you know. ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________Independent Practice: Spicy Last year, there were 24 boys and 20 girls on the LPBS Chess Team. This year, the number of boys increased by 25%, and the number of girls decreased by 20%.(a) How many boys are in the chess club this year? (b) How many girls are in the chess club? (c) By what percent did the overall membership change from last year to this year?Mathletes1) The perimeter of a rectangle is 40 cm. If the length of the rectangle is 4 and the width is x+3, which equation would help you solve for x?(a) 82x+3=40(b) 8+2x+3=40(c) 8 + 2(x +3) = 40(d) 4+2x+3=402) The coldest temperature ever recorded in Havana, Cuba is -13.45 degrees Celcius. The difference between the coldest and warmest temperature in Cuba is 129.55 degrees. What is the warmest temperature in Cuba, measured in degrees Celcius?(a) -197.45(b) -116.1(c) 116.1(d) 197.453) Mr. Berkowitz buys a history textbook which costs $89. The tax on his purchase is 4.5%; what is the dollar amount that Mr. Berkowitz pays in taxes?(a) $4.01(b) $4.50(c) $84.55(d) $93.014) The price of a sandwich is expected to increase by 8.5% next year due to inflation. If the sandwich costs x dollars this year, which expression correctly gives the cost of the sandwich next year? (a) 1.85x(b) 1.085x(c) x+0.085(d) 1+0.085Name________________________Date_______________7.RP.3 Class ____________Percent Error Exit Ticket1. Mr. and Mrs. Obama are checking out their daughter’s college dorm room. Mr. Obama estimates the height of the chair to be 46 inches. Mrs. Obama estimates the length of the bed to be 200 inches. A picture of the actual dorm room is below:228600-190500161925130492500321945014630400034759902013585020000-207645164465020000Without doing any calculations, which parent had a smaller percentage error in their estimate? Explain how you know.____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________Find the percent error for each parent. Round to the nearest whole percent.Name________________________Date_______________7.RP.3 Class ____________Percent Error HomeworkMekhi uses his thermometer and finds the boiling point of ethyl alcohol to be 75o C. He looks in a reference book and finds that the actual boiling point of ethyl alcohol is 80o C. What is his percent error? An object has a mass of 35.0 grams. On Keith’s balance, it weighs 30.85 grams. What is the percent error of his balance? One year there were 36 students on honor roll. The next year there were 90 students. By what percent did the number of honor roll students increase?Ms. Shah is training for a race. On Saturday she ran 83 minutes, and on Sunday she ran 76 minutes. By what percent did the time of her training decrease?Mixed ReviewMr. Golini puts $150 into a savings account. He earns $15 in interest. What percent of his original balance does he have now?165%110%10%90%None of the above.Ms. Capellan takes a driving test and receives a score of 12. On the next test, she earns a score of 10. By what percent did her score decrease?2%20%~17%80%83%When Ms. Impink was younger, she could lift 100 pounds. If she increases her weightlifting abilities by 110%, how much can she lift now?110 pounds210 pounds10 pounds11,000 poundsMs. Griffith is planning for her wedding. She predicts that 75 guests will come. She is very surprised when 125 guests attend! What is Ms. Griffith’s percent error?50%~66% 40%None of the above. ................
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