10.

My answer was = 1.58 ( 3.1-3)/0.6/90

The manager of Macey's grocery store has taken a random sample of 90 customers. The average length of time it took the customers in the sample to check out was 3.1 minutes with a standard deviation of 0.6 minutes. We want to test to determine whether or not the mean waiting time of all customers is significantly more than 3 minutes. The test statistic is

(round the final answer to two decimal places, e.g. 2.57)