Question

1. 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 .

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   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: 40 percent of the customers ask for Package 1, 30 percent for Package 2, 20 percent for Package 3, and 10 percent for Package 4. The company will install an additional washing machine to do service A. Answer the following questions based on this new situation.

   e. What is the implied utilization rate for the washing machines? 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 .

   f. 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 .

   g. 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

Solution a:

The capacity rate of the employee is the number of customers that the employee can serve in a given day.

Minutes of work per customer for Employee at Service D = 20 mins

Total availability per day = 10 hrs = 10*60 = 600 minutes

So, the Capacity rate for the employee at Service D = 600 / 20 = 30 customers per day.

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Solution b:

The employee at service C addresses customers who purchase Package 3 (Cleaning) as well as Package 4 (Wash + Wax + Cleaning). The implied utilization rate for the employee at service C is calculated as follows:

The utilization rate for the employee at service C = Total actual effort by the employee at Service C / Total available effort for the employee at Service C = 320 / 600 = 53.33%

Thus, the utilization rate for the employee at Service C is 53.

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Solution c:

The automated wash machine addresses customers who purchase all 4 packages:

• Package 1 (Wash);
• Package 2 (Wash + Wax);
• Package 3 (Wash + Wax + Wheel); and
• Package 4 (Wash + Wax + Wheel + Interior).

The utilization rate for the Auto Wash = Total actual effort by the Auto Wash / Total available effort for the Auto Wash = 500 / 600 = 83.33%

Thus, the utilization rate for Auto Wash is 83.

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Solution d:

Following are the resource utilization rates:

Input 1 - Auto Wash = 83.33%

Input 2 - Wax = 75.00%

Input 3 - Employee at Wheel Cleaning = 53.33%

Input 4 - Employee at Interior Cleaning = 41.67%

So, the highest utilization rate belongs to Input 1 - Auto Wash.

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The detailed calculation for solution a, b, c, and d are shown below:

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Solution e:

Since 2 Auto Wash machines are now available, the total available effort for Auto Wash is = 600 * 2 = 1200 mins

The utilization rate for the Auto Wash = Total actual effort by the Auto Wash / Total available effort for the Auto Wash = 800 / 1200 = 66.67%

Thus, the utilization rate for Auto Wash is 67.

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Solution f:

The utilization rate for the employee at service C = Total actual effort by the employee at Service C / Total available effort for the employee at Service C = 384 / 600 = 64.00%

Thus, the utilization rate for the employee at Service C is 64.

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Solution g:

Following are the projected resource utilization rates for next summer:

Input 1 - Auto Wash = 66.67%

Input 2 - Wax = 140.00%

Input 3 - Employee at Wheel Cleaning = 64.00%

Input 4 - Employee at Interior Cleaning = 26.67%

So, the highest utilization rate belongs to Input 2 - Auto Wax.

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The detailed calculations for solution d, e, and f are shown below: