An automated car wash serves customers with the following serial process: pre-treat, wash, rinse, wax, hand dry. Each of these steps is performed by a dedicated machine except for the hand dry step, which is performed manually on each car by one of 2 workers. The steps of the process have the following processing times:
Pre-treat: 5 min per car.
Wash: 4 min per car.
Rinse: 2 min per car.
Wax: 4 min per car.
Hand dry: 12 min per car.
(a) If the car wash has a demand of 20 cars per hour, what is the flow rate of the process?(Round to nearest integer)
(b) If the car wash has a demand of 15 cars per hour, what is the utilization of the machine that performs the wax process? (Round to the nearest integer)