Chapter 07, section 7.6, problem 066ab a company makes auto batteries. they claim that of their ll70 batteries are good for months or longer. assume that this claim is true. let be the proportion in a random sample of such batteries that are good for months or more.

An automobile assembly line operation has a scheduled mean completion time, μ, of 12 minutes. the standard deviation of completion times is 1.6 minutes. it is claimed that, under new management, the mean completion time has decreased. to test this claim, a random sample of 33 completion times under new management was taken. the sample had a mean of 11.2 minutes. assume that the population is normally distributed. can we support, at the 0.05 level of significance, the claim that the mean completion time has decreased under new management? assume that the standard deviation of completion times has not changed.