A queueing network consists of two servers 1 and 2 in series. Server 1 is subject to a homogeneous Poisson input with intensity λ = 5 an hour. A customer is lost if server 1 is busy. From server 1 a...

A queueing network consists of two servers 1 and 2 in series. Server 1 is subject to a homogeneous Poisson input with intensity λ = 5 an hour. A customer is lost if server 1 is busy. From server 1 a customer goes to server 2 for further service. If server 2 is busy, the customer is lost. The service times of servers 1 and 2 are exponential with respective mean values

All arrival and service times are independent.

What percentage of customers (with respect to the total input at server 1) is served by both servers?