Question:There are four copying center/file rooms serving a relatively large and active legal research firm. One attendant staffs each service room. The average arrival rate and service rate are the same for each room and are as follows:

Arrival rate = 10.9 arrivals per hour

Service rate = 14.6 services per hour

The coefficients of variation of the inter-arrival times and the service times are both equal to 1.

Although the relationships between the average number of arrivals and the average service capacity of each room seem to indicate that a line should rarely exist, most of the time a line of some length has been observed. Sometimes there is no line, and the attendant has nothing to do of any consequence. Management is concerned about this situation because of the lost effectiveness involved in having lawyers idle while researchers are waiting in line for files or other services, and because room attendants are sometimes not performing any work.

Costs are given as follows:

Cost of waiting time = $15.45/hour

Cost of channel time = $6.30/hour

While being mindful of cost, management wants to improve utilization and reduce the queues. If management combines therooms, would it help to add attendants to the combined rooms?

A No, rooms should not be combined

B No, rooms should be combined, but it does not help costs to add attendants

C Yes, management should add 1 attendant to the combined room

D Yes, management should add 2 attendants to the combined room