operations

Chapter 10

1. Fresh Foods Grocery is considering redoing its facility layout. The from–to matrix showing daily customer trips between departments is shown in Table 10-10, and their current layout is shown in Figure 10-12. Fresh Foods is considering exchanging the locations of the dry groceries department (A) and the health and beauty aids department (F). Compute the ld score for Fresh Foods' current and proposed layouts. Which is better?

TABLE 10-10 From–To Matrix for Fresh Foods

FIGURE 10-12 Current layout for Fresh Foods

2. Use trial and error to find a better layout for Fresh Foods Grocery in Problem 1. Compute the ld score and compare it to the ld scores computed for Fresh Foods’ current and proposed layouts. Which is best?

5. Gator Office Systems is comparing two layouts for the design of its office building. It has interviewed managers in order to develop the from–to matrix shown in Table 10-12. The two layouts considered are shown in Figure 10-14. Which layout do you think is better for Gator Office Systems, using the load– distance model?

TABLE 10-12 From–To Matrix for Gator Office Supplies

FIGURE 10-14 Current and proposed layouts for Gator Office Supplies

6. Use trial and error to develop a better layout for Gator Office Supplies. Which departments do you think need to be in close proximity to one another?

8. David's Sport Supplies is a store that sells sports equipment and gear for teenagers and young adults. David's is in the process of assigning the location of storage areas in its warehouse (Figure 10-16) to minimize the number of trips made to retrieve needed items. Given here in Table 10-14 are the departments that need to be located, the number of trips made per week for each department, and the area needed by each department.

TABLE 10-14 Department Information for David's Sport Supplies

FIGURE 10-16 Warehouse storage areas for David's Sport Supplies

10. Michael Marc, the President of MMS Associates, is considering an alternative plan for the sales staff situation described in Problem 9. His alternative plan is shown in Figure 10-18. What is the ld score for this plan? How does it compare to the original plan considered in Problem 9?

FIGURE 10-18 Alternative office locations for sales staff at MMS Associates

18. A dress-making operation is being designed as an assembly line. Table 10-22 shows the tasks that need to be performed, their task times, and preceding tasks. If the goal is to produce 30 dresses per hour, answer the questions that follow the table.

TABLE 10-22 Dress-Making Task Information

· (a) Compute the cycle time.

· (b) Which task is the bottleneck?

· (c) What is the maximum output for this line?

· (d) Compute the theoretical minimum number of stations.

· (e) Assign work elements to stations, using the longest task time rule.

· (f) Compute the efficiency and balance delay of your assignment.

Chapter 11

1. Given the following information, determine the sample size needed if the standard time estimate is to be within 5 percent of the true mean 97 percent of the time.

2. Using the information in Problem 1, determine the sample size needed if the standard time estimate is to be within 5 percent of the true mean 99 percent of the time.

4. Using the information in Problem 3, calculate the sample size needed if the standard time estimate is to be within 5 percent of the true mean 99 percent of the time. Calculate the percentage increase in sample size for the higher precision.

Use the following information from the Arkade Company for Problems 5–10.

12. Frank's Fabricators has collected the following information to develop a standard time for producing their high-volume Navigator III, a universal remote control. All of the times are in minutes.

· (a) Calculate the mean observed time for each element.

· (b) Calculate the normal time for each element.

· (c) Using an allowance factor of 15 percent of job time, calculate the standard time for each element.

· (d) Calculate the standard time for completing one Navigator III.

· (e) If an employee is able to produce at a rate equal to the standard (100 percent efficiency), how many units should she produce each hour?

· (f) If an employee is working at 90 percent efficiency, how many units should she complete in one hour?

· (g) If a process improvement has changed the mean observed time for element 6 to 1.50 minutes, what is the new standard time for the Navigator III?

(h) If the company builds 20,000 Navigator IIIs each month, how much less time does it require using the new process?

14. You have 25 observations of university policeman Sgt. Jack B. Nimble during his normal workday. The results are shown here. Assume that the estimated proportion is to be within 5 percent of the true proportion 95 percent of the time.

Activity Observed	Number of Times Observed
Doing paperwork	9
On the phone	3
Eating doughnuts	3
Cleaning weapon	4
Idle	2
Not in sight	4

· (a) Based on your preliminary observations, how many total observations do you need to estimate the proportion of time Sgt. Nimble spends doing paperwork?

· (b) How many total observations do you need to estimate the proportion of time Sgt. Nimble spends on the phone?

· (c) How many total observations do you need to estimate the proportion of time Sgt. Nimble seems to be unavailable?

16. As a class project you have been asked to project the proportion of time a professor spends on various activities. You have decided to use the work-sampling method. Your initial observations are shown.

Activity Observed	Number of Times Observed
Grading	4
Administrative paperwork	6
Preparing for class	5
Teaching class	5
Meeting with student(s)	8
On the phone	2
Working on research	6
Unavailable	4

You are instructed that your estimates are to be within 5 percent of the true value with 97 percent confidence (z = 2.17).

· (a) Based on your initial observations, how many total observations are needed to estimate the proportion of time the professor spends on each activity?

After taking additional observations, the following data are available.

Activity Observed	Number of Times Observed
Grading	30
Administrative paperwork	50
Preparing for class	30
Teaching class	30
Meeting with student(s)	66
On the phone	17
Working on research	45
Unavailable	34

· (b) Determine what proportion of time the professor spends teaching class.

· (c) Determine what proportion of time the professor spends working on research.

(d) If the professor works approximately 54 hours per week, determine the amount of time that would normally be spent on each activity.