The Rain Cafe aims to launch its first drive$-$through. They decided to

have two drive$-$through lanes $($servers are identical; assume there is a

single queue for both servers$).$ The service time for each drive$-$through

lane is exponentially distributed with a mean of $3$ minutes. The arrival

rate of customers to Rain Caf$$ is Poisson with a rate of $30$ per hour.

a$.$ Using Kendall$$s Notation $($A$/$S$/$c$),$ what type of queueing system is

this?

b$.$ What is the average customer$$s time in the system?

c$.$ If Rain wants to keep the average time in the system for all

customers less than $5$ minutes, do you suggest they increase the

number of lanes?