Chapter 10: Q. 26 (page 625)
Construct and interpret a confidence interval for in Exercise . Explain what additional information the confidence interval provides.
Short Answer
We are confident that the proportion difference is between and .
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Chapter 10: Q. 26 (page 625)
Construct and interpret a confidence interval for in Exercise . Explain what additional information the confidence interval provides.
We are confident that the proportion difference is between and .
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Suppose the true proportion of people who use public transportation to get to work in the Washington, D.C., area is In a simple random sample of people who work in Washington , what is the standard deviation of the sampling distribution of ?
(a)
(b)
(c)
(d)
(e)
A researcher wants to determine whether or not a five-week crash diet is effective over a long period of time. A random sample of 15 dieters is selected. Each person's weight is recorded before starting the diet and one year after it is concluded. Based on the data shown below (weight in pounds), can we conclude that the diet has a long-term effect, that is, that dieters managed to not regain the weight they lost? Include appropriate statistical evidence to justify your answer.

Based on your answer to Question 3, would you be surprised if the difference in the proportion of red crackers in the two samples was ? Explain.
Toyota or Nissan? Are Toyota or Nissan owners more satis铿乪d with their vehicles? Let鈥檚 design a study to 铿乶d out. We鈥檒l select a random sample of Toyota owners and a separate random sample of Nissan owners. Then we鈥檒l ask each individual in the sample: 鈥淲ould you say that you are generally satis铿乪d with your (Toyota/Nissan) vehicle?鈥
(a) Is this a problem with comparing means or comparing proportions? Explain.
(b) What type of study design is being used to produce data?
46. Happy customers As the Hispanic population in the United States has grown, businesses have tried to understand what Hispanics like. One study inter-viewed a random sample of customers leaving a bank. Customers were classified as Hispanic if they preferred to be interviewed in Spanish or as Anglo if they preferred English. Each customer rated the importance
of several aspects of bank service on a 10-point scale. Here are summary results for the importance of 鈥渞eliability鈥 (the accuracy of account records and so on):

(a) The distribution of reliability ratings in each group is not Normal. A graph of the data reveals no outliers. The use of two-sample t procedures is
justified. Why?
(b) Construct and interpret a confidence interval for the difference between the mean ratings of the importance of reliability for Anglo and
Hispanic bank customers.
(c) Interpret the confidence level in the context of this study.
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