QUESTION $23$

$M{M}^2$ has a queuing problem where customers who line up to pay their selections form the waiting line. The MM$^2$ system consists of an arrival rate of $12$ per hour according to a Poisson distribution, and service times are on average equal to $4$ minutes per customer.

What is the average waiting time in the queue in minutes?

a$.3$

b$.20$

c$.0\mathrm{.}80$

d$.4\mathrm{.}74$

$$ e$.16$