Reconsider the tire testing experiment described in Exercise 8-22.
(a) The engineer would like to demonstrate that the mean life of this new tire is in excess of 60,000 kilometers. Formulate and test appropriate hypotheses, and draw conclusions using a = 0.05.
(b) Suppose that if the mean life is as long as 61,000 kilometers, the engineer would like to detect this difference with probability at least 0.90. Was the sample size n = 16 used in part (a) adequate? Use the sample standard deviations as an estimate of σ in reaching your decision.