The Average Number of Customers That Visited a Particular Store

Multiple Choice

The average number of customers that visited a particular store during the past year is 160 per day and a standard deviation of 25 customers per day.A random sample of 64 days is chosen from this population.The standard deviation of the sample mean equals:

A) 12.649.
B) 25.0.
C) 2.56.
D) 3.125.
E) 8.0