Concept explainers
A
Interpretation: In order to minimize the mean flow time, the sequence of these jobs are to be determined subject to the precedence instructions.
Concept Introduction: Under the mean flow time, the
B
Interpretation: In order to minimize the mean flow time, the sequence of these jobs are to be determined subject to the precedence instructions.
Concept Introduction: Under the mean flow time, the schedule to be defined will be the sum of time required for executing all tasks in the system.
C
Interpretation: In order to minimize the maximum lateness; determine the sequence of these jobs subject to the precedence instructions.
Concept Introduction: The job sequencing process is the process in which the jobs are arranged in a particular order.
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Production and Operations Analysis, Seventh Edition
- WorkPro is a small manufacturer. It uses a job process for production. The following sample of jobs are listed in the order that they were received. Job Due Date Operation Time P 5 1 Q 20 8 R 8 5 S 11 6 T 3 12 When the shortest operating time (SOT) rule is applied to the sample of jobs, the resulting sequence is: A. Choos the following answer choice. T, P, R, S, Q R, S, T, P, Q P, Q, R, S, T P, R, S, Q, T B. In the WorkPro example above, average flow time for the sample of jobs when sequenced by the shortest operating time (SOT) rule is approximately: 19.8 14.2 4.8 6.4 C. In the WorkPro example above, average lateness for the sample of jobs when sequenced by the earliest due date (EDD) rule is approximately: Group of answer choices 10.4 4.8 7.8 5.8 D. Using the sample of jobs in the WorkPro example above, the shortest operating time (SOT) rule appears more attractive than the earliest due date (EDD) rule…arrow_forwardCourtney 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. JOB DUE DATE (HOURS HENCE) 18 36 10 22 14 E a) Sequence the jobs according to EDD. According to the EDD rule, the sequence of jobs should be b) What is the average completion (flow) time? The average completion (flow) time is c) What is the average job lateness? The average job lateness is d) What is the average number of jobs in the system? The average number of jobs in the system is place). DURATION (HOURS REQUIRED) 3 19 4 9 5 days (round your response to one decimal place) days (round your response to one decimal place). jobs (round your response to one decimalarrow_forwardCurrently 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_forward
- A computer center has two identical computers for batch processing. Thecomputers are used as parallel processors. Job times are estimated by the user, but experience has shown that an exponential distribution gives an accurate description of the actual job times. Suppose that at a point in time there are eight jobs remaining to be processed with the following expected job times (expressed in minutes):Job 1 2 3 4 5 6 7 8Expected time 4 8 1 50 1 30 20 6a. In what sequence should the jobs be processed in order to minimize theexpected completion time of all eight jobs (i.e., the makespan)?b. Assume that computer A is occupied with a job that has exactly two minutes of processing time remaining and computer B is idle. If job times are deterministic, show the start and end times of each job on each computer using the sequence derived in part (a).arrow_forwardConsider the following tasks that must be assigned to four workers on a conveyor-paced assembly line (i.e., a machine-paced line flow). Each worker must perform at least one task. There exists unlimited demand unless stated otherwise. Time to Complete Task (seconds): Task 1: 30 Task 2: 25 Task 3: 15 Task 4: 20 Task 5: 15 Task 6: 20 Task 7: 50 Task 8: 15 Task 9: 20 Task 10: 25 Task 11: 15 Task 12: 20 The current conveyor-paced assembly-line configuration assigns the workers in the following way: • Worker 1: Tasks 1, 2, 3 • Worker 2: Tasks 4, 5, 6 • Worker 3: Tasks 7, 8, 9 • Worker 4: Tasks 10, 11, 12 What is the direct labor content (in seconds per unit)?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
- In her last semester at SPC, Polly Hedron needs to take Statistics, Composition 2, and Ethics. Because Polly is registering early, she has 17 choices for her section of Statistics, 11 choices for her section of Composition, and 19 choices for her section of Ethics. From how many possible schedules can Polly choose? (You may presume that none of these sections interfere with each other) Your Answer:arrow_forwardThe manager of the Personnel Department at City Enterprises has been reading about time-driven ABC and wants to apply it to her department. She has identified four basic activities her employees spend most of the their time on: Interviewing, Hiring, Assessment, and Separation Processing. The department employs 5 staff who perform these activities. The manager provides the following estimates for the amount of time it takes to complete each of these activities: Interviewing: 45 minutes. Hiring: 60 minutes. Assessment: 75 minutes. Separation Processing: 90 minutes. Employees in Personnel work 35-hour weeks with four weeks for vacation. Of the 35 hours, five are reserved for administrative tasks, training, and so on. The costs of the Personnel Department, including any allocated costs from other staff functions, are $972,000. During the year, Personnel conducted 1,200 interviews, made 375 hires, made 3,000 assessments, and had 250 separations. The manager of the Personnel…arrow_forwardThe times required to complete each of eight jobs in a two-machine flow shop are shown in thetable that follows. Each job must follow the same sequence, beginning with machine A and moving to machine B.a. Determine a sequence that will minimize makespan time.b. Construct a chart of the resulting sequence, and find machine B’s idle time. c. For the sequence determined in part a, how much would machine B’s idle time be reduced bysplitting the last two jobs in half?TIME (hours)Job Machine A Machine Ba 16 5b 3 13c 9 6d 8 7e 2 14f 12 4g 18 14h 20 11arrow_forward
- In her last semester at SPC, Polly Hedron needs to take Statistics, Composition 2, Ethics, and Physics. Because Polly is registering early, she has 14 choices for her section of Statistics, 19 choices for her section of Composition, 17 choices for her section of Ethics, and 18 choices for her section of Physics. From how many possible schedules can Polly choose? (You may presume that none of these sections interfere with each other) Your Answer:arrow_forwardGiven the following information on job times and due dates. Job Job Time(Hours) Due Date(Hours) a 3.5 7 b 2.0 6 c 4.5 18 d 5.0 22 e 2.5 4 f 6.0 20 a-1. Determine the optimal processing sequence using (1) First come, first served, (2) Shortest processing time, (3) Earliest due date, and (4) Critical ratio. Sequence for First come, first served Sequence for Shortest processing time Sequence for Earliest due date Sequence for Critical ratio a-2. For each method, find the average job flow time and the average job tardiness. (Round your answers to 2 decimal places.) First Come, FirstServed Shortest ProcessingTime Earliest Due Date Critical Ratio Average flow time Average job tardinessarrow_forwardFive jobs must be scheduled for batch processing on a mainframe computer system. The processing times and the promised times for each of the jobs are listedhere.Job 1 2 3 4 5Processing time 40 min 2.5 hr 20 min 4 hr 1.5 hrPromised time 11:00 A.M. 2:00 P.M. 2:00 P.M. 1:00 P.M. 4:00 P.M.Assume that the current time is 10:00 A.M.a. If the jobs are scheduled according to SPT, find the tardiness of each job and themean tardiness of all jobs.b. Repeat the calculation in part (a) for EDD schedulingarrow_forward
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