Diane Has Been Asked to Consider Plans to Add the Retrieval

Multiple Choice

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?

A) 10 minutes
B) 5 minutes
C) 15.5 minutes
D) 18.5 minutes