a study on students drinking habits asks a random sample of 170 female uf students how many alcoholic beverages they have consumed in the past week. the sample reveals an average of 4.05 alcoholic drinks, with a standard deviation of 4.66. construct a 99% confidence interval for the true average number of alcoholic drinks all uf female students have in a one week period.

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.