One operator services a group of five machines. Machine run time and service durations are both Exponential. Machines run for an average of 85 minutes after a service, and service duration averages 40 minutes. The operator receives $24 per hour in wage and fringe benefits, and machine downtime costs $72 per hour per machine. Refer to the able18-6 for D and F values. (Round the final answers to 2 decimal places.) a. If each machine produces 60 pieces per hour while running, find the average hourly output of each machine when waiting and service times are taken into account. Effective output pieces per hour per machine b. Determine the optimum number of operators