Parts arrive at a two-machine system according to an exponential interarrival distribution with mean 20 minutes; the f rst arrival is at time 0. Upon arrival, the parts are sent to Machine 1 and processed. The processing-time distribution is TRIA(4.5, 9.3, 11) minutes. The parts are then processed at Machine 2 with a processing-time distribution as TRIA(16.4, 19.1, 20.8) minutes. The parts from Machine 2 are directed back to Machine 1 to be processed a second time (same processing-time distribution as the f rst visit but an independent draw from it). The completed parts then exit the system. Run the simulation for a single replication of 20,000 minutes to observe the average number in the machine queues and the average part cycle time.