This is a manual $($hand$)$ simulation. Five customers arrive at a drive thru

during the first $25$ minutes of the day. Arrival and service times are

recorded. The table below shows the results:

You are particularly interested in the following

metrics $($all for the first $25$ minutes of the day$)$:

a$.$ What $\%$ of time is the cashier idle from

time $0?$

b$.$ What is the average time a customer

spends at the drive thru?

c$.$ What is the maximum queue size?

Assume that there are initially no customers at the drive thru.