Q3.7 (Car Wash Supply Process) CC Car Wash specializes in car cleaning services.
ID: 462156 • Letter: Q
Question
Q3.7 (Car Wash Supply Process) 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:
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 40 customers per day. Of these customers, 40 percent buy Package 1, 15 percent buy Package 2, 15 percent buy Package 3, and 30 percent buy Package
4. The mix does not change over the course of the day. The store operates 12 hours a day.
a. What is the implied utilization of the employee doing the wheel cleaning service?
b. Which resource has the highest implied utilization?
For the next summer, CC Car Wash anticipates an increase in the demand to 80 customers per day. Together with this demand increase, there is expected to be a change in the mix of packages demanded: 30 percent of the customers ask for Package 1, 10 percent for Package 2, 10 percent for Package 3, and 50 percent for Package
4. The company will install an additional washing machine to do service A.
c. What will be the new bottleneck in the process?
d. How many customers a day will not be served? Which customers are going to wait? Explain your reasoning!
Cachon, Gerard; Terwiesch, Christian. Matching Supply with Demand: An Introduction to Operations Management (Page 52). McGraw-Hill Education. Kindle Edition.
Explanation / Answer
The given data is summarized as shown below:
Customer/day
40
Operating Hours
12
Package
Package Mix (%)
Number of customer per day
Number of customer per hour
P 1
40
40*40/100 = 16
16/12 = 1.33
P 2
15
15*40/100 = 6
6/12 = 0.5
P 3
15
15*40/100 = 6
6/12 = 0.5
P 4
30
140*40/100 = 2
2/12 = 1
Implied Utilization = Requested Capacity/Available Capacity) x 100
Service
Time (min/car)
Resource Used
Available Capacity
(car/hour) (c/b*60)
Requested Capacity (Cars per hour)
Implied Utilization =(Req. Cap./Avail. Cap.)
P1
P2
P3
P4
Total
a
b
c
A. Wash
10
1 automated washing machine
6
1.33
0.5
0.5
1
3.33
55.50%
B.
Wax
10
1 automated waxing machine
6
0
0.5
0.5
1
2
33.33%
C. Wheel Cleaning
7
1 employee
8.57
0
0
0.5
1
1.5
17.50%
D. Interior Cleaning
20
1 employee
3
0
0
0
1
1
33.33%
a. What is the implied utilization of the employee doing the wheel cleaning service?
Ans: 17.50%
b. Which resource has the highest implied utilization?
Ans: Automated washing machine has the highest implied utilization of 55.50%
Utilization calculation for next summer
Customer/day
80
Operating Hours
12
Package
Package Mix (%)
Number of customer per day
Number of customer per hour
P 1
30
30*80/100 = 24
24/12 = 2
P 2
10
10*80/100 = 8
8/12 = 0.67
P 3
10
10*80/100 = 8
8/12 = 0.67
P 4
50
50*80/100 = 40
40/12 = 3.33
Service
Time (min/car)
Resource Used
Available Capacity
(car/hour) (c/b*60)
Requested Capacity (Cars per hour)
Implied Utilization =(Req. Cap./Avail. Cap.)
P1
P2
P3
P4
Total
a
b
c
A. Wash
10
2 automated washing machine
12
2
0.67
0.67
3.33
6.67
55.58%
B.
Wax
10
1 automated waxing machine
6
0
0.67
0.67
3.33
4.67
77.83%
C. Wheel Cleaning
7
1 employee
8.57
0
0
0.67
3.33
4
46.67%
D. Interior Cleaning
20
1 employee
3
0
0
0
3.33
3.33
111.00%
c. What will be the new bottleneck in the process?
The new bottleneck is Service D, Interior Cleaning, because the implied utilization of this resource is more than 100% with highest implied utilization of 111.00%.
d. How many customers a day will not be served? Which customers are going to wait? Explain your reasoning!
Ans:Some of the customers opting for package 4 will not be served as the service D resource capacity is less than requested capacity.
No. of customer not being served = (Requested capacity/hr – Available capacity/hr) x 12
= (3.33 – 3) x 12 = 3.96 ~ 4 customers per day.
Customer/day
40
Operating Hours
12
Package
Package Mix (%)
Number of customer per day
Number of customer per hour
P 1
40
40*40/100 = 16
16/12 = 1.33
P 2
15
15*40/100 = 6
6/12 = 0.5
P 3
15
15*40/100 = 6
6/12 = 0.5
P 4
30
140*40/100 = 2
2/12 = 1
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.