A Bank of 10 Machines Requires Regular Periodic Service

Multiple Choice

A bank of 10 machines requires regular periodic service. Machine running time and service time are both exponential. Machines run for an average of 44 minutes between service requirements, and service time averages six minutes per machine. If operators cost $15 per hour in wages and fringe benefits and machine downtime costs $75 per hour in lost production, what is the optimal number of operators for this bank of machines?

A) 1
B) 2
C) 3
D) 4
E) 5