Chapter 7 Section 1 - Portland Community College



Chapter 7 Section 1

Homework Set B

Data is available at CrunchIt! site: bcs.crunchit/ips6e

On the left side of the worksheet page you will see a links to chapters; click on chapter 7, then select appropriate Exercise.

7.32 Food intake and weight gain. If we increase our food intake, we generally gain weight. Nutrition scientists can calculate the amount of weight gain that would be associated with a given increase in calories. In one study, 16 nonobese adults, aged 25 to 36 years, were fed 1000 calories per day in excess of the calories needed to maintain a stable body weight. The subjects maintained this diet for 8 weeks, so they consumed a total of 56,000 extra calories.12 According to theory, 3500 extra calories will translate into a weight gain of 1 pound. Therefore, we expect each of these subjects to gain 56,000/3500 = 16 pounds (Ib). Here are the weights before and after the 8-week period expressed in kilograms (kg):

A) Describe the distribution using graphical methods. Is it appropriate to analyze these data using methods based on Normal distributions?

(a) For each subject, subtract the weight before from the weight after to determine the weight change.

(b) Find the mean and the standard deviation for the weight change.

(c new) Theory suggest that the weight gain by the individuals should be 16lbs on average. Is there any evidence to suggest that the average weight gain is different? Run a significance test, and use a 5% confidence level. Write down the null and alternative hypothesis, the necessary calculations, the p-value, and the conclusion.

(c) Calculate the standard error and the margin of error for 95% confidence. Report the 95% confidence interval in a sentence that explains the meaning of the 95%.

(f) Write a short paragraph explaining your results.

34. Potential insurance fraud? Insurance adjusters are concerned about the high estimates they are receiving from Jocko's Garage. To see if the estimates are unreasonably high, each of 10 damaged cars was taken to Jocko's and to another garage and the estimates recorded. Here are the results:

Test the null hypothesis that there is no difference between the two garages. Be sure to specify the null and alternative hypotheses, the test statistic with degrees of freedom, and the P-value. What do you conclude? If the result provides good evidence against the null, then create a 95% confidence interval.

A) Describe the distribution using graphical methods. Is it appropriate to analyze these data using methods based on Normal distributions?

7.35 Fuel efficiency comparison t test. Refer to Exercise 7.24. In addition to the computer calculating mpg, the driver also recorded the mpg by dividing the miles driven by the amount of gallons at fill-up. The driver wants to determine if these calculations are different.

Problem 24 Computers in some vehicles calculate various quantities related to performance. One of these is the fuel efficiency,..

A) Describe the distribution using graphical methods. Is it appropriate to analyze these data using methods based on Normal distributions?

(a) State the appropriate Ho and Ha.

(b) Carry out the test. Give the P-value, and then interpret the result.

(c) If the result is statistically significant at the 1% level calculate a 95% confidence interval and interpret what the interval is trying to tell us.

7.44 Property damage due to tornadoes. Table 1.5 (page 25) gives the average property damage per year due to tornadoes for each of the 50 states and Puerto Rico. It does not make sense to use the t procedures (or any other statistical procedures) to give a 95% confidence interval for the mean property damage per year due to tornadoes in the United States. Explain why not.

................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download