A Drive Thru Car Wash Can Process Cars at a Rate

Multiple Choice

A drive thru car wash can process cars at a rate of one every five minutes. The manager notices that during one particular day it takes cars an average of about 30 minutes in line to reach the car wash. What was the average number of cars in line on that day?

A) 1 to 3 cars
B) 4 to 6 cars
C) 7 to 9 cars
D) 10 or more cars