A drive through liquor store estimates that customers arrive in their cars at the rate of 10 per hour. The cashier can serve customers at a rate 15 per hour. What is the average waiting time in line?

4 minutes

Explanation:

Availability

time = 60 minutes

Capacity = 15 cars per hour

Time taken for each car to serve = 60 / 15 minutes = 4 minutes

Arrival of car

Cars per hour = 10 cars

Time taken by each car = 60 / 10 = 6 minutes per car

As cars are arriving later than the time taken to serve each so the average time in line will be 4 minutes