The tool crib at a large manufacturing company is responsible for providing tools to the factory workers on demand. The tool crib has a variable demand. Historically, its demand has ranged from 150 to 250 small tools per day with an average of 200. Diane, the tool crib attendant, works eight hours a day, five days a week. Each order is for one small tool and each small tool takes Diane 2 minutes to retrieve from the bins.
Diane has been asked to consider plans to add the retrieval of larger tooling fixtures to her duties. She anticipates that there would be an average of 12 tooling fixtures per day requested. Each tooling fixture would take Diane 4 minutes to retrieve.
What is the average waiting time, in minutes, if Diane continues to be the only worker that would retrieve the small tools as well as the larger tooling fixtures?

Select one:

A. 5.0 minutes

B. 10.0 minutes

C. 15.5 minutes

D. 18.5 minutes

E. 31.0 minutes