Answer the following questions:

$($a$)$ what is the average inter$-$arrival time for the average arrival rate of $=15$ customers$/$hour$?$

$($b$)$ For each of the following average service times, what is the average service rate for an average service time

of $1/=2$ minutes?

$($c$)$ Customers arrive at an ATM on campus at an average rate of $30$ per hour. The average number of people

waiting for their turn to use the ATM is $4.$ What is the average waiting time?