Management Chapter 15 Homework There is little difference in these sequences since each has 4 jobs that are late. The EDD sequence minimizes the maximum lateness

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37. The minimum number of part-time employees needed at a quick service restaurant for

each two-hour block is shown in the following table:

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Let X1 through X7 be the number of employees assigned to a four-hour shift beginning at

time block 1 through 7.

The objective function is to minimize X1 + X2 + X3 + X4 + X5 + X6 + X7

To ensure that the minimum number of employees are available at each time block, we

have the following constraints:

X1 >= 12

X1 + X2 >= 6

The Excel model (with the optimal solution), formulas, and Solver model (available on the

Instructor site) are shown below.

38. David Chris is running the season’s final basketball tournament for Youth Boosters. He is

trying to schedule the referee crews for each game. The following table shows the number

of times in the past that each crew has refereed a game for that team. David wants to

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The spreadsheet with Solver solution (available on the Instructor site) is shown below. The

assignment does not have any previous pairings of the referees with teams.

39. An earth moving machine had five jobs in the same area it must complete as soon as

possible. Sequence the jobs using (a) FCFS order 1-2-3-4-5, and (b) the SPT rule. Use the

Sequencing Excel template to compute performance measures for both sequences. What

sequence is better?

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FCFS sequence

SPT sequence

40. Mike Reynolds has four assignments due in class tomorrow, and his class times are as

follows.

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three, four, and two hours, respectively. Use the Excel Sequencing template to determine

how he should schedule the work. Can he complete all of it on time?

First, convert times to due dates past midnight:

Job Processing time Due date

—–——— ———–—————–—— ———––

1 Marketing 4 8

SPT sequence:

EDD sequence:

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41. Tony’s Income Tax Service personnel can estimate the time required to complete

customers’ tax returns by using the following time standards assuming all information is

available.

One morning, five customers are waiting, needing the following forms filled out. They

arrived in the order A-B-C-D-E.

Use the Excel Sequencing template to answer the following questions:

a. If these customers are processed on a FCFS basis, what is the flow time for each and the

average flowtime?

b. If SPT is used, how will these performance metrics differ?

First, compute the amount of time needed for each customer:

Customer Forms Time

A 1040 long, schedules A and B 35

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a.

b.

42. Four blood samples have arrived in your laboratory with the following information.

Use the Excel Sequencing template for the following:

a. Sequence the jobs using the SPT rule.

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b. Sequence the jobs using the EDD rule.

c. Compare average flow time, average and maximum lateness, average and maximum

tardiness, and makespan for these two sequencing rules and compare the results.

43. A bank’s mortgage department must process the following six jobs to maximize client

satisfaction. What sequencing rule should you use? What sequencing rule should you use?

For the rule you selected, find the best sequence using the Excel Sequencing template.

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Because there are due dates, the EDD rule is most appropriate for the objective of client

satisfaction (minimize maximum lateness and tardiness). The EDD sequence is 2 (first), 4, 5,

44. A manufacturing firm makes custom orthopedic parts for human knee, hip, and shoulder

replacements. Because shipping the custom part(s) prior to the scheduled surgery date is

essential, compare the SPT and EDD rules, and recommend the best sequencing rule for

this situation. Use the Excel Sequencing template to evaluate each rule.

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SPT sequence:

EDD sequence:

The SPT rule minimizes average flowtime (20.5 versus 21.25) and delivers three of four jobs

on time. However, Job 4 is 12 days late. The EDD sequence is superior on the tardiness

measures. EDD’s average lateness is -1.75 versus -2.50 for SPT, and the maximum a job is

45. An insurance claims work area has five claims waiting for processing as follows.

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Use the Excel Sequencing template to find the average flowtime, average and maximum

tardiness, and average lateness for the following sequences: SPT sequence, EDD sequence,

and the sequence 2-1-5-3-4. What sequencing rule do you recommend and why?

SPT sequence:

EDD sequence:

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2-1-5-3-4 sequence:

There is little difference in these sequences since each has 4 jobs that are late. The EDD

sequence minimizes the maximum lateness. Note that the last sequence based on

46. Eight jobs have arrived in the following order:

Find and compare the performance measures for the following sequencing rules using the

Excel Sequencing template:

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a. Process in the order they have arrived

b. Shortest processing time

c. Earliest due date