Question

CC Car Wash specializes in car cleaning services. The services offered by the company, the exact service time, and the resources needed for each of them are described in the table following:

Service	Description	Processing Time	Resource
A. Wash	Exterior car washing and drying	10 minutes	1 automated washing machine
B. Wax	Exterior car waxing	15 minutes	1 automated waxing machine
C. Wheel Cleaning	Detailed cleaning of all wheels	16 minutes	1 employee
D. Interior Cleaning	Detailed cleaning inside the car	20 minutes	1 employee

The company offers the following packages to their customers:

• Package 1: Includes only car wash (service A).

• Package 2: Includes car wash and waxing (services A and B).

• Package 3: Car wash, waxing, and wheel cleaning (services A, B, and C).

• Package 4: All four services (A, B, C, and D).

Customers of CC Car Wash visit the station at a constant rate (you can ignore any effects of variability) of 50 customers per day. Of these customers, 30 percent buy Package 1, 30 percent buy Package 2, 15 percent buy Package 3, and 25 percent buy Package 4. The mix does not change over the course of the day. The store operates 10 hours a day.

a. Define “minute of work” as the flow unit, what is the capacity rate of the employee at the interior cleaning step per day? Round the answer to the nearest whole number. For example, if your answer is 2543.65, round to 2544; if you answer is 2543.12, round to 2543.

Your answer is .

b. What is the implied utilization rate for the employee at service C (wheel cleaning)? Round your answer to the nearest whole number and ignore the percentage sign. For example, if your answer is 0.45 or 45%, fill in 45; if your answer is 0.76 or 76%, fill in 76.

Your answer is .

c. What is the implied utilization rate for the automated washing machine? Round your answer to the nearest whole number and ignore the percentage sign. For example, if your answer is 0.45 or 45%, fill in 45; if your answer is 0.76 or 76%, fill in 76.

Your answer is .

d. What resource has the highest utilization rate? Input 1 for washing machine, input 2 for waxing machine, input 3 for employee at C, input 4 for employee at D.

Your answer is .

Answer 1

a.

The Capacity Rate of all the resources at the car cleaning service is given as :

where the formula for capacity rate for interior cleaning is is :

Capacity Rate = Number of Hours Available*60/ Processing Time = 10*60/20 = 30

b.

and to calculate the utilization rate :

we use the formula :

Utilization Rate = Total Workload / Capacity Rate

So the utilization rates of all the services are calculated as :

Service	Processing Time	Number of Resources	Capacity Rate	Total Workload	Utilisation = Total Workload/Capacity Rate
Washing	10	1	60	50	0.833333333
Waxing	15	1	40	35	0.875
Wheel Cleaning	16	1	37.5	20	0.533333333
Interior Cleaning	20	1	30	12.5	0.416666667

So the utilization rate for Wheel Cleaning is = 0.5333*100 = 53 % ( Round Off) = 53

c.

The utilization rate of the automated washing machine as shown in the above table is :

= Utilisation = Total Workload/Capacity Rate = 50/60*100 = 83 % = 83 ( Round off )

d.

As we can see from the table the highest utilization rate is of Waxing i.e The 1 automated waxing machine which is given as 0.875*100 = 87.5 %. i.e answer is input 2

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