Z00042. An automated car wash serves customers with the following serial process : pretreat, 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 three workers. The steps of the process have the following processing times :
- Pretreat : 1 minute per car
- Wash : 6 minutes per car
- Rinse : 2 minutes per car
- Wax : 3 minutes per car
- Hand dry : 4 minutes per car
(a) Which resource is the bottleneck of the process ?
(b) If the car wash has a demand of 12 cars per hour, what is the flow rate of the process ?
(c) If the car wash has a demand of 12 cars per hour, what is the utilization of the machine that performs the wax process ?
(d) If the car wash has a demand of 8 cars per hour, what is the utilization of hand dry ?