Answer to Question #501 in Statistics and Probability for Dee

Question

Clients arrive at random every 25 minutes on average at a careers advice center where there is only one adviser. Find the mean number of clients in the center, either receiving advice or waiting for advice, if the time spent by the adviser with a client (i) is constant and equal to 20 minutes (ii) has a uniform distribution, being anything between 10 minutes and 30 minutes.