A Department Has 5 Machines That Each Run for an Average

Essay

A department has 5 machines that each run for an average of 8.4 hours (exponential)before service is required.Service time average is 1.6 hours (exponential).
(i)While running,each machine can produce 120 pieces per hour.With one server,what is the average hourly output actually achieved?
(ii)With 2 servers,what is the probability that a machine would be served immediately when it requires service?
(iii)If machine downtime cost is $100 per hour per machine,and server time costs $30 per hour,how many servers would be optimal?