A radio machine on an average finds 5 customers coming to his shop every hour for repairing their radio sets. He disposes of each of them within 10 minutes on an average. The arrival and servicing…

A radio machine on an average finds 5 customers coming to his shop every hour for repairing their radio sets. He disposes of each of them within 10 minutes on an average. The arrival and servicing times follow Poisson and exponential distribution respectively. In the light of the above facts determine: a) Proportion of time during which his shop remains empty. b) The average no. of customers in his system and queue. c) The average time spent by a customer in the queue and the service as well. d) The probability of finding at least five customers in his shop.