Operations Management
17th Edition
ISBN: 9781259142208
Author: CACHON, Gérard, Terwiesch, Christian
Publisher: Mcgraw-hill Education,
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Chapter 18, Problem 3PA
Summary Introduction
To determine: Average flow time of the projects in FCFS sequence.
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Courtney is a programmer receiving requests each week to analyze a large data base. Five jobs were on her desk Monday morning and
she must decide in what order to write the code. Assume that all jobs arrived today (day 1 and hour 1), in the order shown below. Courtney
has assigned the number of hours required to do the coding as noted. Note that Courtney works an 8-hour day and today is a work day.
Due date
Duration (hours
required)
Job
(hours hence)
A
8
16
2
C
24
10
32
16
E
12
6
In what sequence would the jobs be ranked according to the following decision rules: FCFS, EDD, SPT, LPT?
According to the FCFS rule, the sequence of jobs should be
According to the EDD rule, the sequence of jobs should be
According to the SPT rule, the sequence of jobs should be
According to the LPT rule, the sequence of jobs should be
The following jobs are waiting to be processed at a small machine center.
JOB
10
20
30
40
50
DUE DATE
260
256
260
265
275
DURATION (DAYS)
According to the LPT rule, the sequence of jobs should be 10, 50, 40, 20, 30
b) What is the average completion (flow) time?
The average completion (flow) time is 62.8 days (round your response to one decimal place)
c) What is the average job lateness?
The average job lateness is 11.0 days (round your response to one decimal place).
d) What is the average number of jobs in the system?
The average number of jobs in the system is jobs (round your response to one decimal place).
28
12
8
18
22
D
Points: 2 of 4
All dates are specified as manufacturing planning calendar days. Assume that all jobs arrived on day 200 (yesterday) in the order shown but are not scheduled to begin until day 201 (today).
a) Sequence the jobs according to LPT
state whether or not each situation would be considered “compensable time” (and why or why not).
An employee of a fast food chain has to arrive at work 15 minutes early to change into the“mascot” costume and it typically takes another 15 minutes at the end of the shift to change outof the costume and properly store it. Due to the cost of the costume, employees are notallowed to take the costume home. The “mascots” typically work from 10am – 2pm, to coverthe lunch rush periods. How much time would be “compensable” for the mascots, assumingthe conditions/schedule listed above?2) George is a Radiology Technician at a local hospital and when on call, is required to be nofurther than 30 minutes away from the facility. Is the “on call” time, compensable?
Chapter 18 Solutions
Operations Management
Ch. 18 - Prob. 1CQCh. 18 - Prob. 2CQCh. 18 - Prob. 3CQCh. 18 - Prob. 4CQCh. 18 - Prob. 5CQCh. 18 - Prob. 6CQCh. 18 - With weighted shortest processing time, jobs are...Ch. 18 - Prob. 8CQCh. 18 - Prob. 9CQCh. 18 - Prob. 10CQ
Ch. 18 - Prob. 11CQCh. 18 - Prob. 12CQCh. 18 - Prob. 13CQCh. 18 - Prob. 14CQCh. 18 - Prob. 15CQCh. 18 - Prob. 16CQCh. 18 - Prob. 1PACh. 18 - Prob. 2PACh. 18 - Prob. 3PACh. 18 - Prob. 4PACh. 18 - Prob. 5PACh. 18 - Prob. 6PACh. 18 - Prob. 7PACh. 18 - Prob. 8PACh. 18 - Prob. 9PACh. 18 - Prob. 10PACh. 18 - Prob. 11PACh. 18 - Prob. 12PACh. 18 - Prob. 13PACh. 18 - Prob. 14PACh. 18 - Prob. 15PACh. 18 - Prob. 1CCh. 18 - Prob. 2CCh. 18 - Prob. 3CCh. 18 - Prob. 4C
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- Currently a company that designs Web sites has six customers in its backlog. The time since the order arrived, processing time, and promised due dates are given in the following table. Job Time Since Order Arrived (days ago) Processing Time (days) Due Date (days from now) A 6 18 48 B 4 22 52 C 1 30 70 D 10 14 28 E 7 12 56 F 5 20 62 Develop a schedule by using the first-come, first-served (FCFS) rule and calculate the average flow time and average days past due for the schedule. Develop a schedule by using the earliest due date (EDD) rule and calculate the average flow time and average days past due for the schedule. Comment on the performance of the FCFS and EDD rules relative to average flow time and average days past due.arrow_forward1/ Katie Posh runs an upscale nail salon. The service process includes five activities that are conducted in the sequence described below. (The time required for each activity is shown in parentheses):Activity 1: Welcome a guest. (1 minute)Activity 2: Clip and file nails. (3 minutes)Activity 3: Paint. (5 minutes)Activity 4: Dry. (10 minutes)Activity 5: Check out the customer. (4 minutes)Three servers (S1, S2, and S3) offer the services in a worker-paced line. The assignment of tasks to servers is the following: S1 does Activity 1. S2 does Activities 2 and 3. S3 does Activities 4 and 5. The drying process does not require server 3’s constant attention; she/he needs to only escort the customer to the salon’s drying chair (equipped with fans for drying). The time to do this is negligible. There exists only one drying chair in the salon.a. What is the utilization of server 2 (in decimal form)? Assume that there is unlimited demand and that the process only admits customers at the rate of…arrow_forwardThe following six jobs are to be scheduled on a single machine: Job 1 2 3 4 5 6 Processing time (min.) 110 120 220 90 180 80 Suppose the jobs are processed in FCFS numerical order. Compute the makespan, flow time for each job, and overall average flow time. Round your answers to the nearest whole number. Job Flow Time (min) 1 2 3 4 5 6 Makespan: minutes Average flow time: minutes In what order would the jobs be processed using the SPT rule? The SPT sequence is - - - - - . Compute the average flow time after each job is completed. Round your answer to the nearest whole number. Average flow time: minutes Compare this answer with your answer to part a. The minimizes flow time and gets the most work done in the least amount of time.arrow_forward
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