Question

A campus deli serves 300 customers over its busy lunch period from 11:30 a.m. to 1:30 p.m. A quick count of the number of customers waiting in line and being served by the sandwich makers shows that an average of 10 customers are in process at any point in time. What is the average amount of time that a customer spends in process?

Answer 1

Consider the following information:

Customers served \(=300\) No. of hours of serving \(=2\) hours Average number of customers in line, \(L_{q}=10\)

Calculate the flow rate as follows:

$$ \begin{aligned} \text { Flow rate } &=\frac{\text { Total customers served }}{\text { Hours of serving }} \\ &=\frac{300}{2} \\ &=150 \end{aligned} $$

Now, use the little law to calculate the average time in process \(\left(W_{q}\right)\) as follows:

$$ \begin{aligned} W_{q} &=\frac{L_{q}}{\text { Flow rate }} \\ &=\frac{10}{150} \\ &=0.067 \text { hours or } 4.02 \text { minutes } \end{aligned} $$