An automobile assembly line operation has a scheduled mean completion time, u, of 12.8 minutes. The standard deviation of completion times is 1.8 minutes. It is claimed that, under new management, the mean completion time has decreased. To test this claim, a random sample of 37 completion times under new management was taken. The sample had a mean of 12.1 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.

Carry your intermediate computations to at least three decimal places, and round your responses as specified in the table.