4. Parts arrive at two machine system according to an exponential interarrival time distribution with a mean 20 minutes. Upon arrival, the parts are sent to machine 1 and processed. The processing time distribution is TRIA (4.5, 9.3, 11.0) minutes. The parts are then processed at machine 2 with a processing time distribution as TRIA (16.4, 19.1, 21.8) minutes. The parts from machine 2 are directed back to machine 1 to be processed a second time (same processing time). 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