Problem 18-11 One operator services a bank of five machines. Machine running time and service time are both exponential.

Problem 18-11

One operator services a bank of five machines. Machine running time and service time are both exponential. Machines run for an average of 81 minutes between service requirements, and service time averages 19 minutes. The operator receives $16 per hour in salary and fringe benefits, and machine downtime costs $80 per hour per machine. Use Table 1, Table 2 and Table 3.

a.If each machine produces 65 pieces per hour while running, find the average hourly output of each machine, when waiting and service times are taken into account.(Round your answer to 2 decimal places.)

  Average hourly output pieces  _______________

b.Determine the optimum number of operators.

 4 operator

2 operators

3 operators