The repair of leather requires four steps to be completed one after another in a certain order. The time taken to perform each step follows exponential distribution with a mean of 10 minutes and is independent of others steps. Machines breakdown follows Poisson process with a mean rate of 3 breakdown per how. Answer the following questions
1. What is the expected idle time of the machines, assuming there is only one repair man available in the workshop.
2. What is the average waiting time of a breakdown maintaining the queue.
3. What is the expected number of broken machines in the queue?