The Manager of a Grocery Store Has Taken a Random

Multiple Choice

The manager of a grocery store has taken a random sample of 144 customers. The average length of time it took these 144 customers to check out was 3 minutes. It is known that the standard deviation of the population of checkout times is 1 minute. With a .95 probability, the sample mean will provide a margin of error of

A) 1.63.
B) .137.
C) .163.
D) 1.37.