An average of 100 customers per hour arrive to the Picayune Mutual Bank. It takes a teller an average of two minutes to serve a customer. Interarrival and service times are exponentially distributed. The bank currently has four tellers working. Bank manager Rich Gold wants to compare the following two systems with regard to the average time customers spend in the bank.

System #1

A separate queue is provided for each teller. Assume that customers choose the shortest queue when entering the bank, and that customers cannot jockey between queues (jump to another queue).

System #2

A single queue is provided for customers to wait for the ?rst available teller. Assume that there is no move time within the queues. Run 15 replications of an eight-hour simulation to complete the following:

a. For each system, record the 90 percent con?dence interval using a 0.10 level of signi?cance for the average time customers spend in the bank.

b. Estimate the number of replications needed to reduce the half width of each con?dence interval by 25 percent. Run the additional replications for each system and compute new con?dence intervals using a 0.10 level of signi?cance.

c. Based on the results from part b , would you recommend one system over the other? Explain.