Production and Operations Analysis, Seventh Edition
7th Edition
ISBN: 9781478623069
Author: Steven Nahmias, Tava Lennon Olsen
Publisher: Waveland Press, Inc.
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Chapter 9, Problem 39AP
Summary Introduction
Interpretation: The performance of the SPT and LPT is to be compared by using a given problem.
Concept Introduction:
Shortest processing time rule is used for the minimization of mean time flow of the project and hence it is used to minimize the time of mean flow of the process. In SPT rule, the sequence of jobs is present in increasing order as per their processing time while in LPT rule; sequence of jobs is present in decreasing order as per their processing time.
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Joe'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. Joe 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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A
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B
3
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E
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Using FCFS, assume the jobs arrive in the order shown (A, then B, then C, etc.). Show the beginning time for each job and ending time for the whole process adding hours throughout the process.
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B-5 number of hours
C-8 number of hours
D-10 number of hours
E-17 number of hours
A
B
C
D
E
0
enter a number of hours
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enter a number of hours
enter a number of hours
enter a number of hours
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You operate a process with three workstations; the cycle times are given below. A regular batch is 52 units and your production line runs 5 hours per day. Calculate how many hours lead time is required to ship a batch, assuming there are no orders ahead in the queue and there is no inventory to fill the order.
Workstation 1 has a cycle time of 2 minutes per unit
Workstation 2 has a cycle time of 3 minutes per unit
Workstation 3 has a cycle time of 3 minutes per unit
Select one:
a. 1560.00
b. 8.00
c. 1560.00
d. 90.00
e. 2340.00
Consider a workstation that has one maintenance mechanic to repair failed machines. We can think of the mechanic as the processor (scarce
resource) and the machines awaiting repair as the jobs. Let us assume that six machines are down, with estimated repair times given here, and
that no new machines fail.
1 2 3
Job (fix
machine #)
Processing time 10
(hours)
Job
1
2
3
4
5
6
2
Compute the flow time for each job using both the FCFS rule and the SPT rule, and compare the average flow times. Round your answers for
average values to the nearest whole number.
FCFS Rule
9
Flow Time (hours)
Average flow time (FCFS rule):
4
5 6
1 8 6
hours
Chapter 9 Solutions
Production and Operations Analysis, Seventh Edition
Ch. 9.5 - Prob. 1PCh. 9.5 - Prob. 2PCh. 9.5 - Prob. 3PCh. 9.5 - Prob. 4PCh. 9.5 - Prob. 5PCh. 9.6 - Prob. 6PCh. 9.6 - Prob. 7PCh. 9.6 - Prob. 8PCh. 9.6 - Prob. 9PCh. 9.6 - Prob. 10P
Ch. 9.7 - Prob. 11PCh. 9.7 - Prob. 12PCh. 9.7 - Prob. 13PCh. 9.7 - Prob. 14PCh. 9.7 - Prob. 15PCh. 9.7 - Prob. 16PCh. 9.7 - Prob. 17PCh. 9.8 - Prob. 18PCh. 9.8 - Prob. 19PCh. 9.8 - Prob. 20PCh. 9.8 - Prob. 21PCh. 9.8 - Prob. 22PCh. 9.9 - Prob. 23PCh. 9.9 - Prob. 24PCh. 9.9 - Prob. 25PCh. 9.10 - Prob. 27PCh. 9.10 - Prob. 28PCh. 9.10 - Prob. 29PCh. 9 - Prob. 30APCh. 9 - Prob. 31APCh. 9 - Prob. 32APCh. 9 - Prob. 33APCh. 9 - Prob. 34APCh. 9 - Prob. 35APCh. 9 - Prob. 36APCh. 9 - Prob. 37APCh. 9 - Prob. 38APCh. 9 - Prob. 39APCh. 9 - Prob. 40APCh. 9 - Prob. 41APCh. 9 - Prob. 42APCh. 9 - Prob. 43APCh. 9 - Prob. 44APCh. 9 - Prob. 45APCh. 9 - Prob. 46APCh. 9 - Prob. 47AP
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