An automobile assembly line operation has a scheduled mean completion time of 12 minutes. The standard deviation of completion times is 1.6 minutes.

An automobile assembly line operation has a scheduled mean completion time 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 41 completion times under new management was taken. The sample had a mean of 11.9 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. Perform a one-tailed test. Then fill in the table below.