An operator is in charge of FIVE machines. After each machine completes a job, the operator must reset it before a new job is started. In other words, the operator’s task is to set up each machine when a job is completed. The time to complete a job on any machine is negative exponential with mean 45 minutes. The time to set up any machine is also negative exponential with mean 8 minutes.
(a) Determine the average number of machines that are awaiting set up or are being set up.
(b) Determine the average time a machine is awaiting set up or are being set up.
(c) What is the probability that all machines are working?