The manager of a local fast-food restaurant is interested in improving the service provided to customers who use the restaurant’s drive-up window. As a first step in this process, the manager asks his assistant to record the time (in minutes) it takes to serve a large number of customers at the final window in the facility’s drive-up system. The given frame of 200 customer service times are all observed during the busiest hour of the day for this fast-food operation. The data are in the file P2_4.XLS. 

a. Compute the mean, median, and standard deviation of the customer service times in the given frame. 

b. Use Excel to choose a simple random sample of size 20 from this frame. 

c. Compute the mean, median, and standard deviation of the service times for the 20 customers included in your simple random sample. Compare these statistics with your computed descriptive measures for the frame obtained in part a.