11. Customers arrive at a two-server system according to a Poisson process having rate = 5....

11. Customers arrive at a two-server system according to a Poisson process having rate ë = 5. An arrival finding server 1 free will begin service with that server. An arrival finding server 1 busy and server 2 free will enter service with server 2. An arrival finding both servers busy goes away. Once a customer is served by either server, he departs the system. The service times at server / are exponential with rates ì,, where ì÷ = 4, ì2 = 2.

(a) What is the average time an entering customer spends in the system?

(b) What proportion of time is server 2 busy?