Customers arrive at Rich Dunn's Styling Shop at a rate of 3 per hour, distributed in a Poisson fashion. Rich can perform haircuts at a rate of 5 per hour, distributed exponentially.

a) Find the average number of customers waiting for haircuts.

b) Find the average number of customers in the shop.

c) Find the average time a customer wafts until it is his or her turn.

d) Find the average time a customer spends in the shop.

e) Find the percentage of time that Rich is busy.