An Introduction to Management Science 13th Edition by David Anderson,Dennis Sweeney ,Thomas Williams ,Jeffrey Camm, Kipp Martin

Exercise 14

Telephone calls come into an airline reservations office randomly at the mean rate of 15 calls per hour. The time between calls follows an exponential distribution with a mean of 4 minutes. When the two reservation agents are busy, a telephone message tells the caller that the call is important and to please wait on the line until the next reservation agent becomes available. The service time for each reservation agent is normally distribution with a mean of 4 minutes and a standard deviation of 1 minute. Use a two-channel waiting line simulation model to evaluate this waiting line system. Use the worksheet design shown in Figure 12.17. The cell formula = -4*LN(RAND()) can be used to generate the interarrival times. Simulate the operation of the telephone reservation system for 600 customers. Discard the first 100 customers, and collect data over the next 500 customers.
a. Compute the mean interarrival time and the mean service time. If your simulation model is operating correctly, both of these should have means of approximately 4 minutes.
b. What is the mean customer waiting time for this system?
c. Use the =COUNTIF function to determine the number of customer who have to wait for a reservation agent. What percentages of the customers have to wait?