Operations Management

Username: Bridgette Newby Book: Operations Management, 4th Edition. No part of any chapter or book may be reproduced or
transmitted
in any form by any means without the prior written permission for reprints and excerfis from the publisher of the
book
or chapter. Redistribution or other use that violates the fair use privilege under U.S. copyright laws (see 17 USC107) or
that othenrise violates these Terms of Service is strictly prohibited. Violators will be prosecuted to the full extent of U.S. Federal
and Massachusetts laws.
(a) Determine the sequence Henri should follow if he uses
the SPT (shortest processing time) priority rule.
(b) Based on the sequence developed in part (a), calculate the
following performance measures: makespan, mean job flow
time,
averagr number of jobs in the system, mean job lateness, mean job tardiness, and maximum tardiness.
6. Henri has decided to try a different priority rule.
(a) Using the data in Problem 5, determine the sequence
Henri should follow if he uses the EDD (earliest due
date)
priority rule.
(b) Based on the sequence developed in part (a), calculate the
following performance measures: makespan, mean job flow
time,
average number of jobs in the system, mean job lateness, mean job tardiness, and maximum tardiness.
7. Henri has heard of the LPT (longest processiag time) priority rule and wonders how that would change the sequence of the
jobs
listed in Problem 5.
(a) Determine the sequence Henri should follow if he uses
the LPT priority rule.
(b) Based on the sequence developed in part (a), calculate the
following performance measures: makespan, mean job
flow time,
average number of jobs in the system, mean job
lateness, mean job tardiness, and maximum tardiness.
8.
In an effort to be tair to his customers, Henri has decided to
use the FCFS (first come, first served) priority rule. Using the job
data from Problem 5, assume that the jobs arrive in order-that
is, A first, then B, then C.
(a) Using the data in Problem 5, determine the sequence
Henri should follow if he uses the FCFS (first come, first
served) priority rule.
(b) Based on the sequence developed in part (a), calculate the
following performance measures: makespan, mean job flow
time,
average number of jobs in the system, mean job lateness, mean job tardiness, and maximum tardiness.
9.
Henri recently learned about global priority rules. He is interested in the slack over remaining operations (S/RO) rule.
(a) Using the data in Problem 5, determine the sequence
Henri should follow if he uses the S/RO priority rule.
(b) Based on the sequence developed in part (a), calculate the
following performance measures: makespan, mean job flow
time,
average number of jobs in the system, mean job lateness, mean job tardiness, and maximum tardiness.
10.
]oe’s Twenty-four Seven Laundromat has the following
jobs waiting to be processed. The first step of the process includes
washing and drying the
clothes; the second step is pressing the
clothing.
|oe wants to minimize the amount of time it takes to do
all the jobs. The five jobs
waiting to be processed are shown here.
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PROBLEMS . 585
(a)
Using FCFS, assume the jobs arrive in the order shown
(A, then
B, then C, etc.). Show the beginning and ending
time for
each job.
(b) Calculate the makespan, the mean job flow time, and the
average number of jobs in the system.
I
l. |oe thinks that it is probably more efficieat to use SPT
(shortest processing
time) as his priority rule.
(a) Develop a sequence using SPT based on processing time
for
the wash and dry operation.
(b) Calculate the makespan, the mean job flow time, and the
average
number of jobs in the system.
12. Joe has asked
you to develop a sequence that minimizes
makespan for the sequence of jobs given in Problem 10. Compare
the
makespan, mean job flow time, and average number of jobs
in
the system to your results in Problems l0 and I 1.
13.
Raquel’s Landscaping Company has contracted for several
landscaping jobs. Each
job requires preparing the areas (identiffiag the locations and types of plants, preparing the soil, etc.) and
then planting the trees, bushes, and shrubs. The expected time
for
each of the jobs is shown next.

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2
3 5 5 4 3
(a) Using FCFS (first come, first served), assume the jobs arrive in the order shown (R, then S, then T, etc.). Show the
beginning and ending time for each job.
(b) Calculate the makespan, the mean job flow time, and the
average
number of jobs in the system.
14. Raquel is concerned with efficiency. She believes it is probably more efficient to use SPT (shortest processing time) as her
priority rule.
(a) Develop a sequence using SPT based on processing time
for preparing
the area.
(b) Calculate the makespan, the mean job flow time, and the
average number of jobs in the system.
15. Raquel
has asked you to develop a sequence that minimizes makespan for the sequence of jobs given in Problem 13.
Compare the makespan, mean job flow time, and average number of jobs in the system to your results in Problems 13 and 14.
16, Barb’s Beach Bar operates seven days per week, Barb uses
only firll-time employees and wants each employee to have two
consecutive days
off each week. She believes that she needs a
minimum of three employees on Monday, Tuesday, Wednesday,
Thursday, and Sunday.
On Friday and Saturday, she believes that
she needs six employees. Develop a worldorce schedule for Barb.
17.
Next week is a three-day weeketd. Barb believes that she
will need a minimum of six employees on Friday, Saturday, and
Sunday. The other
days will still need a minimum of three workers.
Remember
that Barb wants each employee to have tlvo consecutive
R
STUVw
Usemame: Bridgette Newby Book: Operations Management, 4th Editipn. No part of any chapter or book may be reproduced or
transmitted
in any form by any means without the prior written permission for reprints and excerpts from the publisher of the
book
or chapter. Redistribution or other use that violates the fair use privilege under U.S. copyright laws (see 17 USC107) or
that othenrise violates these Terms of Service is strictly prohibited. Violators will be prosecuted to the full extent of U.S. Federal
and Massachusetts laws.
584 . CHAPTER 1s SCHEDULING
8. Explain how finite loading is done.
9. Explain the benefits
of finite loading.
10. Describe forward scheduling.
11. Describe backward scheduling.
12. Visit a local service or manufacturing operation and learn
how
it measures schedule effectiveness.
Problems
1. Jack, the owner and manager of Jack’s Box Company, wants
to monitor
usage at Work Center 3, which is a bottleneck in the
system.
He has collected data on the planned and actual input
and output.
Input Information
(in
hours)
13. Describe the principles of OPT.
14. Describe the theory of constraints.
15. Describe different methods that might be useful for scheduling service operations,
Inout Information (in hours)
456
Planned input
Actual input
Deviation
Cumulative deviation
40 50 50
25 35 35
50 50
40 40
0utput Information (in hours)
Planned input
Actual input
Deviation
Cumulative deviation
40
45
50 50 60 60
4s 45 55 60
456
Planned output
Actual output
Deviation
Cumulative deviation
Backlog 75 hours
40 50 50
45 45 45
60 60
55 60
&utput Iilfslrrfiati$n
(in hours)
Plaaned output
Actual output
Deviation
Cumulative deviation
Backlos 75 hours
(a) Complete the input/output record.
(b) Describe your concerns based on the results of the
inputloutput
analysis.
2. Since Iack believes
that Work Center 3 is his bottleneck, he
has asked
you to do the following:
(a) Calculate the percentage of planned output needed to
complete
the planned inputs (planned input * bacHog/
planned output)
at Work Center 3.
(b) Calculate the percentage of planned input that actually
happened (actual
input + backlog/planned input *
backlog).
(c) Calculate the percentage of available output that was actually accomplished (actual output/planned output) at
Work Center 3.
(d) Given your results, do you believe that Jack is correct in
assuming that Work Center 3 is his bottleneck? |ustifr
your answef.
3. Based on
your concerns, Jack has gathered the following information for Work Center 2, the work center that directly feeds
Work Center 3. Complete the input/output analysis of Work
Center 2.
Complete the iirput/output record.
Describe your concerns based on the results of the
input/output
analysis.
4. lack has asked you to calculate the following for Work
Center 2.
(a) Calculate the percentage of planned output needed to
complete the planned inputs (planned
input * bacHog/
planned output)
at Work Center 2.
(b) Calculate the percentage of planned input that actually
happened (actual input + bacHog/planned input * backlog) at Work Center 2.
(c) Calculate the percentage of available output that was
actually accomplished (actual output/planned output)
at Work Center 2.
(d) What insights can you offer }ack about Work Centers 2
and
3?
5. Henri’s Custom Gowns has six jobs waiting to be processed.
Each
gown is at the beading work center. The job information is
shown here.
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