$($b$)$ Dom & Derry Car Wash $($DDCW$)$ is the only car wash in a small town. A relatively large

number of people who live in the town are their customers. The customers arrive following a

Poisson distribution at an average of eight car wash customers per hour. Cars wait in a single

waiting line and follow an FCFS queue discipline until they can be washed. Dom and Derry

installed an automatic car washer, which takes a constant time of six minutes per car to wash.

$($b$-1)$ How many car wash customer$/$s would they expect to serve at DDCW on average?

$($b$-2)$ What is the average time in minutes a car wash customer will spend waiting to be served?