You can then keep on adding employees

to the point where this constraint is honored.

So this is quite an easy way to find a staffing plan.

You can do this for one time slot in isolation, but also consider the situation

where you have seasonal demand as illustrated on the earlier slide.

Seasonal demand simply means

that the inter-arrival times are actually changing over the course of the day.

There are 60 minutes in an hour, and so if I have 30 customers arrive in an hour,

I have an inter-arrival time of two.

When demand gets busier, I have a shorter inter-arrival time.

So say for the sake of argument,

I have some times in the day when there are not 30 customers arriving.

But, there are 50 customers arriving.

When you enter arrival time, in this case

would simply be 60 minutes in an hour divided by 50 customers in an hour,

which means there's a customer coming in every 1.2 minutes.

Notice that this blows up our waiting-time formula.

At that point actually our implied utilization is bigger than one and

our formula does not apply.

I have to keep on adding employees to make this staffing feasible.

If I add from three to four employees

I have an average waiting time of two point five minutes.

If I have a goal as articulated earlier as having a response time

under two minute waiting time.

Well let's see if five minutes was a job, five employees to the job and you notice

that I can just increment my m to the point where the constraint is fulfilled.