A national grocer's magazine reports the typical shopper spends six minutes in line waiting to check out. A sample of 16 shoppers at the local Farmer Jack's showed a mean of 5.1 minutes with a standard deviation of 2.8 minutes. Is the waiting time at the local Farmer Jack's less than that reported in the national magazine? Use the 0.02 significance level.
(a) What is the decision rule? (Negative amount should be indicated by a minus sign. Round your answer to 3 decimal places.)