When a person exercises, the cells of the body need more oxygen. this is achieved by the system increasing the amount of oxygen that is supplied to the blood and the system increasing the rate of delivery of the blood to the cells of the body.

A. digestive; circulatory
B. circulatory; digestive
C. respiratory; cardiovascular
D. cardiovascular; respiratory

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.