Problem 1: (60 pts) This question is based on the Starbucks’ Operations In-Class Exercise. Some information is modified and additional…

Problem 1: (60 pts) This question is based on the Starbucks’ Operations In-Class Exercise. Some information is modified and additional information is provided, so please read carefully.

The following information is available about the operations of a local Starbucks store.

A. There are three employees in the store:

Cashier who takes all orders and pours drip coffee.

Frozen drink maker who prepares blended and iced drinks.

Espresso drink maker who prepares espressos, lattes and steamed drinks.

B. Three types of drinks are offered:

Drip coffee: takes the cashier 20 seconds on average to pour a cup of coffee.

Blended and iced drink: takes the frozen drink maker 2 minutes on average to make one.

Espresso drink: takes the Espresso drink maker 1.5 minutes on average to make one.

C. Average customer demand rate (i.e., ) for each type of drink:

Drip coffee: 50 per hour.

Blended and iced drink: 20 per hour.

Espresso drink: 40 per hour.

We also know that each customer spends 20 seconds on average with the cashier to order and pay.

Questions:

(1)   (10 pts) Calculate the utilization of the three employees.

(2)  (10 pts) As an effort to improve operations, the manager has cross-trained the frozen drink maker and the Espresso drink maker, i.e., now each of them can make both frozen and espresso drinks. What is the utilization of the two drink makers combined, i.e., if we consider the two drink makers as a workstation, what is the utilization of the workstation?

(3)  (10 pts) Recently, the store has experienced a change in demand pattern. Specifically, the average customer demands for the three drinks are:

Drip coffee: 65 per hour.

Blended and iced drink: 15 per hour.

Espresso drink: 30 per hour.

Calculate the utilization of the cashier and the drink maker workstation (i.e., assume that cross-training is done as in Part (2)).

(4)  (10 pts) Given the new demand scenario presented in Part (3), the manager has decided to shift the responsibility of pouring coffee to the two drink makers and let the cashier focus solely on taking orders and payments. Assume that each of the two drink makers also spends 20 seconds pouring a cup of coffee. Based on the average demand data in Part (3), calculate the utilization of the cashier and the drink maker workstation (i.e., assume that cross-training is done as in Part (2)).

(5)  (20 pts) Given the new demand scenario presented in Part (3) and the change made in Part (4), in order to serve customers better, the manager has collected additional data to assess customers’ estimated waiting time before they can order, i.e., the waiting time before they are served by the cashier. The manager knows that the coefficient of variations of the customer demand process (i.e., the arrival process) and the cashier (i.e., the service process) are 1 and 1.3, respectively. Calculate the followings:

1. How long on average does a customer have to wait before ordering?
2. On average, how many customers are waiting to have their orders taken (DO NOT include customers waiting for their drinks)?
3. With the upcoming opening of a nearby office building, the manager estimates that the total demand rate (including all three types of drinks) will increase by 30%. What will be the waiting time before ordering given this 30% increase? What is the percentage increase of waiting time compared to that obtained in (a)? What is the percentage increase of waiting time compared to that obtained in (a) if the total demand rate increases by 60%?

Problem 2: (30 pts) The following information is available about the operations of a call center.

There are three departments in this call center:

• Sales Department that handles all calls related to placing new orders, and has 10 representatives.
• Return Department that handles all calls related to product return requests from customers, and has 8 representatives.
• Service Department that handles all other types of calls, mainly including warranty and billing issues, and has 9 representatives.

On average,

• Each representative in the Sales Department takes 5 minutes to answer one call;
• Each representative in the Return Department takes 6 minutes to answer one call; and
• Each representative in the Service Department takes 10 minutes to answer one call (regardless of call type).

On average, the call center receives 200 calls per hour, where 50% of the calls are for the Sales Department, 26% of the calls are for the Return Department, 18% of the calls are for warranty related issues, and the rest of the 6% are for billing related issues.

Calculate the utilization of the three departments.

Problem 3: (20 pts) Draw a Pareto diagram for the following car repair shop data. What type of work does the shop perform most frequently?

Problem 4: (10 pts) Prepare a scatter plot for the following data set and then express in words the apparent relationship between the two variables. Put the first variable on the horizontal axis and the second variable on the vertical axis.

Problem 5: (30 pts) Checkout time at a supermarket is monitored. Six samples of n = 10 observations have been obtained and the sample means and ranges computed:

1. (10 pts) Create an x-bar chart for this process and plot the samples on the x-bar chart. How would you interpret the chart?  i.e. What does it tell you?

1. (10 pts) Create a R-chart for this process and plot the samples on the R chart. How would you interpret the chart?  i.e. What does it tell you?

1. (10 pts) If the service specification of the checkout time is between 2.5 and 3.5 minutes, what is the process capability measure for this checkout process? Is it a capable process?

Problem 6: (20 pts) An inspector counted the number of defective monthly billing statements of a company telephone in each of the 10 samples. Using the following information, construct a p-chart and discuss the result. Each sample contained 100 statements.