An athlete recorded her practice times running a course.

Chapter 9, Problem 9.3.24

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An athlete recorded her practice times running a course. She had eight times recorded when she ran in the morning and these had a sample average of 132.52 minutes with a standard deviation of 1.31 minutes. In addition, she had ten times recorded when she ran in the afternoon and these had a sample average of 133.87 minutes with a standard deviation of 1.72 minutes. (a) Is there sufcient evidence to conclude that the morningandafternoonareanydifferentonaverage?Usean appropriatehypothesistesttoinvestigatethisquestion. (b) Construct a two-sided 99% condence interval for the differencebetweentheaverageruntimeinthemorning and the average run time in the afternoon.9.3.25 A random sample of 10 observations from population A has a sample mean of 152.30 and a sample standarddeviation of 1.83. A random sample of 8 observations from population B has a sample standard deviation of 1.94. If the p-value for the one-sided hypothesis test with an alternative hypothesis HA : A > B is less than 1%, what can you say about the sample mean of the observations from population B?