Answer:
The average customer waits in the system for 0.3 hours or 18 minutes.
Explanation:
We can work with this as a queuing theory problem.
The observation of 20 customers arriving per hour is the rate of arrival λ=20 1/hour.
The 6 customers in the branch office is L, the mean number of customers in the system (being serviced or waiting).
We need to calculate W, which is the average time in the system (waiting or being serviced).
For that we can use the Little's rule, tha can be written as
[tex]L=\lambda*W[/tex]
In that case,
[tex]W=L/\lambda=6/20=0.3 \,hours[/tex]
The average customer waits in the system for 0.3 hours or 18 minutes.