Consider a job shop that consists of M machines and one serviceman. Suppose that the amount of time each machine runs before breaking down is exponentially distributed with mean 1/λ, and suppose that the amount of time that it takes for the serviceman to ?x a machine is exponentially distributed with mean 1/μ. We shall attempt to answer these questions: (a) What is the average number of machines not in use? (b) What proportion of time is each machine in use?