Potential customers arrive at a fast-food take-out according to a Possion process with average rate of 3 customers per minute. Potential customers enter only if there is space inside the restaurant. There are two servers. The service times are exponentially distributed with an average service time of 30 seconds. The restaurant can hold a maximum of 4 customers. Therefore this is an M/M/2/4 queue. Compute L and W.
L=long-run average number of customers in the system, W=the average time a customer spends in the system.