Problem $18-11($Static$)$

One operator services a bank of five machines. Machine running time and service time are both exponential. Machines run for an average of $90$ minutes between service requirements, and service time averages $35$ minutes. The operator receives $$20$ per hour in salary and fringe benefits, and machine downtime costs $$70$ per hour per machine. Use Table $1,$ Table $2$ and Table $3.$

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. $($Round your answer to $2$ decimal places.$)$

Average hourly output

pieces