The manager of a grocery store has taken a random sample of 36 customers. The average length of time it took the customers in the sample to check out was 4.2 minutes. The population standard deviation is known to be 0.4 minute. We want to test to determine whether or not the mean waiting time of all customers is significantly more than 4 minutes. Refer to Exhibit 9-22. The test statistic is . Question 4 options: 1.96 1.65 2.00 3.00