Executives blood pressure Example 10.12 (page 500) found

Chapter 10, Problem 10.40

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Executives blood pressure Example 10.12 (page 500) found that the mean blood pressure of a sample of executives did not diff er signifi cantly at the 10% level from the national mean, which is 128. Use the data in that example to give a 90% confi dence interval for the mean of the companys executive population. Why do you expect 128 to be inside this interval? Exercises 10.41 to 10.43 refer to the following setting. A bank wonders whether omitting the annual credit card fee for customers who charge at least $2400 in a year will increase the amount charged on its credit cards. The bank makes this offer to an SRS of 200 of its credit card customers. It then compares how much these customers charge this year with the amount that they charged last year. The mean increase in the sample is $332, and the standard deviation is $108.