OM3 Ch 14 Operations Scheduling and Sequencing

Chapter 14—Operations Scheduling and SequencingTRUE/FALSE 1. Scheduling refers to determining the order in which jobs or tasks are processed. ANS: F PTS: 1 2. Telling an umpire crew to work baseball games in Chicago, then Milwaukee, and then Cleveland is an example of a sequence. ANS: T PTS: 1 3. Scheduling and sequencing methods used in manufacturing are more beneficial in low-contact, than high-contact, service processes. ANS: T PTS: 1 4. Scheduling problems occur almost exclusively in manufacturing. ANS: F PTS: 1 5. Appointments can be viewed as a reservation of service time and capacity. ANS: T PTS: 1 6. Indirectly, appointments reduce the cost of providing a service because the service provider is idle less each workday. ANS: T PTS: 1 7. Sequencing is not as much of a concern when several activities use a common resource. ANS: F PTS: 1 8. Flow time is the amount of time a job spends in a shop or factory. ANS: T PTS: 1 9. The makespan is the sum of flow times of a given set of jobs. ANS: F PTS: 1 10. High flow times reduce WIP inventory. ANS: F PTS: 1 11. A lateness measure can only be 0 or a positive number. ANS: F OM3 Test Bank PTS: 1 Chapter 14 1 A tardiness measure can be either zero (0) or a positive number. Since all jobs eventually get done. In practice. When several products share common facilities. The EDD rule minimizes the maximum of jobs past due but doesn't perform well on average flowtime. Tardiness measures the amount of time by which the completion time exceeds the due date. In sequencing jobs in a flow shop with two resources.12. Johnson's rule finds a sequence that has the smallest makespan. job sequencing has no effect on resource utilization. Like the SPT rule. whenever processing times of a set of jobs are about equal. ANS: T PTS: 1 23. the earliest due date (EDD) rule minimizes the average flow time. For a single processor. ANS: T PTS: 1 21. product sequencing affects cost. ANS: T OM3 Test Bank PTS: 1 Chapter 14 2 . ANS: T PTS: 1 13. managers typically use a firstcome. ANS: F PTS: 1 19. first-served (FCFS) rule minimizes the average flow time because customer waiting time will be minimized. ANS: F PTS: 1 14. In sequencing a set of jobs on a single processor. ANS: T PTS: 1 18. ANS: F PTS: 1 22. first-serve rule. The shortest processing time rule and earliest due date rule will always provide the same sequence. ANS: F PTS: 1 17. ANS: F PTS: 1 20. a first-come. ANS: T PTS: 1 16. different sequences will have different makespans but the same average flow times. ANS: F PTS: 1 15. WIP inventory or resource utilization. The SPT sequencing rule will maximize the average flow time. Gantt charts can show what jobs are ahead of schedule. Triage by nurses in an emergency room would be an example of a. the world's largest package delivery company. is highly dependent on scheduling but not sequencing. The due date for each job c. Scheduling refers to specifying a. Scheduling applies to all aspects of the value chain. The start and completion times of jobs d. UPS. Flow-time estimates b. Accurate forecasting c. Appointments systems often overbook to maximize revenue. ANS: F PTS: 1 27. and on schedule. Appointments d. ANS: T PTS: 1 28. Staffing levels required by time period OM3 Test Bank Chapter 14 3 . Scheduling b. Shortest-processing-time rule ANS: B PTS: 1 2. ANS: T PTS: 1 26.24. ANS: T PTS: 1 29. The time to rest and travel between games for baseball umpire crews is an important factor in developing their schedule. The sequence that jobs must be completed b. behind schedule. Rescheduling rarely occurs unless customers change their requested due dates. Two examples of process-focused performance measures for sequencing rules are flow time and lateness. ANS: F PTS: 1 25. Sequencing c. ANS: T PTS: 1 MULTIPLE CHOICE 1. The makespan of each job ANS: C PTS: 1 3. ANS: F PTS: 1 30. Staff scheduling needs all of the following except a. Flow time b. Determining the appointment time interval b. Least work remaining ANS: B PTS: 1 9.d. first served d. Ready time c. Determining the length of each workday and the time off-duty d. Deciding on an overbooking policy ANS: B PTS: 1 5. Makespan d. The Shortest Processing Time (SPT) rule a. Due date ANS: C PTS: 1 6. The goal is to minimize makespan d. Earliest due date c. Tardiness ANS: B PTS: 1 7. Ensures that due dates are met b. Makespan d. The sequencing rule that minimizes the maximum number of jobs that are past due from a given set of jobs is a. Determining available personnel ANS: A PTS: 1 4. First come. Lateness c. Each job can be processed by either resource first ANS: C OM3 Test Bank PTS: 1 Chapter 14 4 . Flow time b. Maximizes average flow-time c. Considering a two-resource sequencing problem. Determining the appropriate sequencing rule c. Shortest processing time b. The makespan is the same for any sequence of jobs b. Which of the following is not a consideration when designing an appointment system? a. The numerical difference between the completion time and the due date is called a. Minimizes work in process inventory ANS: D PTS: 1 8. a. Minimizes resource utilization d. Flow time is minimized c. The time needed to process a given set of jobs is called a. 10. c. b. c. PTS: 1 PTS: 1 16. The least remaining operations d. If the highest priority is to minimize the average job lateness. Decide how much to overbook for each day of the week. c. Only two jobs can be processed at a time through each work center d. ScheduleAnywhere. A requirement of Johnson’s two-resource sequencing rule is a. The chief disadvantage of the shortest processing time rule is: average job completion times are excessive average number of jobs in the system is excessive long-duration jobs may have excessive completion times average job lateness is excessive ANS: C a. See who's scheduled and who's available. Which of the following is NOT a criterion for evaluating job sequencing rules? average flow time lateness tardiness sum of processing times ANS: D a. c. d. d. The shortest processing time b. b. Johnson’s sequencing rule is used to sequence several jobs through several work centers several jobs through one work center two jobs through several work centers several jobs through two work centers OM3 Test Bank Chapter 14 5 . ANS: B PTS: 1 12. Total processing time must be minimized ANS: B a. d. The smallest critical ratio c. d. Jobs must be processed through each work center in the same job sequence c. c. PTS: 1 15. 13. The longest processing time ANS: A PTS: 1 11. PTS: 1 14. d. then the jobs sequence should begin with those jobs requiring a. All jobs must begin at the same time b. b. b.com on-line software helps clients do all the following except a. b. Which of the following is an example of a situation for which a Gantt chart would be appropriate? developing a factory layout tracking inventory levels over time monitoring job schedules forecasting personnel requirements in a two-shift operation ANS: C a. Avoid scheduling conflicts. Schedule employees from any computer with Internet access. ANS: OM3 Test Bank Chapter 14 6 . Accurately forecasting demand and translating it into the quantity and timing of work to be done – using a capacity measure like number of staff required 2. tax preparers. Differentiate between scheduling and sequencing.ANS: D PTS: 1 SHORT ANSWER 1. Staff scheduling attempts to match available personnel with the needs of the organization by performing what four steps? ANS: 1. and sometimes in 5. insurance agents. Scheduling refers to the assignment of start and completion times to particular jobs. sickness. and incorporates start and completion times. Develop customer appointment rules PTS: 1 4. and reduce customer waiting time. Determine the length of each workday and the time off-duty 3. Decide how to handle overbooking 4. A sequence generally specifies a schedule. dentists. Determine the appointment time interval 2. and developing a work schedule that maximizes service and minimizes costs – different approaches are required for different situations because of the nature of scheduling constraints PTS: 1 3.to 10-minute time intervals 3. Matching capacity to demand requirements. Determining the personnel available and the full. PTS: 1 2. people or equipment. The four major decisions required to design an appointment system as described in the text are: 1. Lawyers. What four (4) decisions are considered in designing an appointment system? ANS: Service capacity is perishable and appointment systems improve resource utilizations and revenue generation. etc. no-shows. personal trainers. 4. ANS: Both scheduling and sequencing involve identifying the order in which jobs or activities are performed. Determining the staffing required to perform the work by time period – usually by hour of the day. investment advisors and consultants are examples of where appointment systems benefit both the customer and service-provider. Compare and contrast the advantages and disadvantages of the Shortest Processing Time (SPT) and the Earliest Due Date (EDD) sequencing rules. physicians. Sequencing refers to determining the order in which jobs or tasks are processed. cable and telephone installers. vacations. personal allowances.and part-time mix – considering worker productivity factors. ANS: 1.SPT and EDD Rules generally work well in the short term but. The EDD Rule minimizes the maximum of jobs past due but doesn't perform well on average flow time. List at least five factors affecting short-term capacity. 4. ANS: The total processing time for all jobs is constant. PTS: 1 7. Find the job with the shortest processing time (on either resource). due to high variability in customer demand. 6. Short-term capacity fluctuations necessitate changes in schedules. The SPT Rule tends to minimize average flow time and work-in-process inventory.. in most situations. Repeat steps 2 and 3. if it corresponds to Resource #2. 2. sequence the job first. 5. new orders and jobs arrive intermittently and the schedule must accommodate them. using the next-shortest processing time and working inward from both ends of the sequence until all jobs have been scheduled. Give at least five examples of service organizations (and employee type) where. In this case. ANS: 1. PTS: 1 6. Describe Johnson's sequencing rule for the two-resource sequencing problem. WIP inventory or resource utilization. 3. 2. sequence the job last. List the jobs and their processing times on Resources #1 and #2. "If a job waits more than 40 hours. it is simply the sum of the individual processing times. PTS: 1 5. staff scheduling problems are prevalent. Call center (service representatives) Hotel (housekeepers) Toll booths (toll collectors) Hospital (nurses) Police department (patrol officers) Airline (reservation clerks) PTS: 1 8. schedule it next. which is sequence independent. If SPT were used in a dynamic environment. 4. and maximize resource utilization. i.") must be used to avoid this problem. M = C  S where M = makespan of a group of jobs C = completion time of last job in the group S = start time of first job in the group so it doesn't change. some time-based exception rule. a job with a large processing time might never get processed. Explain why any sequence chosen in the single-machine scheduling problem will not change makespan time. 3. OM3 Test Bank Chapter 14 7 .e. If this time corresponds to Resource #1. ANS: 1. Days Due From Today 12 9 6 7 20 Use the Shortest Processing Time Rule (SPT) and determine the average flow-time for the five jobs Use the Earliest Due Date Rule (EDD) and determine the average lateness and tardiness. Customer-focused due date criteria: two common measures are lateness and tardiness. and material handling. b . Cost-based criteria: common cost measures include inventory holding. Lateness is the difference between the completion time and the due date (either positive or negative). Processing Time (days) 8 4 3 7 5 Job A B C D E a. 3. processing. changeover (setup). are given below. Tardiness is the amount of time by which the completion time exceeds the due date.6 days b. Lateness calculations are shown below: Job Flow time OM3 Test Bank Lateness Chapter 14 Tardiness 8 . Flow times are C 3 B 3+4=7 E 7 + 5 = 12 D 12 + 7 = 19 A 19 + 8 = 27 Average flow time = 13. Sequence the jobs as C-B-E-D-A. Sequence the jobs C-D-B-A-E. Explain the three categories of criteria used to evaluate job sequencing performance. ANS: Process-focused performance criteria: two common measures are flow time and makespan. The following five jobs. For each category. Makespan is the time needed to process a given set of jobs. 2. PTS: 1 PROBLEM 1. 5. along with their processing time and due dates. 4. 1. Employee absenteeism (and turnover) Sub-par labor performance Equipment (including power) failures Tooling (including set-up) problems Material shortages PTS: 1 9. 2. 3. provide two example measures. ANS: a. Flow time is the amount of time a job spent in the shop or factory. b.8 days PTS: 1 OM3 Test Bank Chapter 14 9 .4 days Average tardiness = 25/5 = 5. Lateness calculations are shown below: Job E A D B C Flow time 10 10 + 16 = 26 26 + 8 = 34 34 + 23 = 57 57 + 22 = 79 Lateness 10 . Flow times are D 8 E 8 + 10 = 18 A 18 + 16 = 34 C 34 + 22 = 56 B 56 + 23 = 79 Average flow time = 39 days b. Processing Time (days) 16 23 22 8 10 Job A B C D E Days Due From Today 24 30 40 28 18 a.C D B A E 3 3 + 7 = 10 10 + 4 = 14 14 + 8 = 22 22 + 5 = 27 3  6 = -3 10  7 = 3 14  9 = 5 22  12 = 10 27  20 = 7 0 3 5 10 7 Average lateness = 4.0 days PTS: 1 2. The table below includes processing times and due dates for five jobs.2 days Average tardiness = 14. Use the Shortest Processing Time Rule (SPT) to determine the average flow time. Sequence the jobs as D-E-A-C-B. Use the Earliest Due Date Rule (EDD) to determine the average lateness.18 = -8 26  24 = 2 34  28 = 6 57  30 = 27 79  40 = 39 Tardiness 0 2 6 27 39 Average lateness = 13. ANS: a. Sequence the jobs E-A-D-B-C. 1 Makespan = 14.0 10.9 5.0 11.1 PTS: 1 4. M 5 4 3 2 2 1 0 Tu 2 2 2 2 2 1 0 W 1 1 1 1 0 0 0 Th 4 3 2 1 0 0 0 F 6 5 4 3 2 1 0 Sa 7 6 5 4 3 2 1 Su 2 1 0 0 0 0 0 PTS: 1 OM3 Test Bank Chapter 14 10 .7 8. they would also like to play golf tomorrow. For the last employee.6 2. state the schedule for each operation.6 Sew Time (hours) 2.9 5. A restaurant needs the following number of wait staff to serve its evening guests. Day: Minimum Number of Wait Staff Needed: M Tu W Th F Sa Su 5 2 1 4 6 7 2 How many employees are needed so that each as two consecutive days off? Construct a work schedule for these employees. They are job shops that handle a variety of outpatient surgical procedures.9 5.0 2.4 9. They want to sequence their patients with the objective of minimizing the time from the beginning of the first job until the finish of that job.6 5.4 9.6 2.8 3. and determine the minimum makespan.7 9. Numbers underlined are the "circled" days in the algorithm that designate days off. ANS: D AB E C Job D A B E C Start Cut 0 0.0 End Cut 0. Their process is set up so that one doctor cuts and the other sews.5 Start Sew 0.7 11.6 14.0 1.5 2.6 End Sew 1. ANS: Seven employees are needed.6 Sequence the patients using Johnson's Method. Since the weather forecast is for a cool and sunny day.0 0. They have five patients to sequence for tomorrow.5 1.3. The patients and estimated times are as follows: Patient A B C D E Cut Time (hours) 2.3 2.6 2.6 3. there are many different options. A new surgical facility called Cut & Sew is opening in neighborhoods throughout the United States. A movie theater requires the following minimum number of employees. Use the days-off scheduling procedure to determine the minimum number of employees required? b. She plans to stay open from 9a. each of which is required to have two consecutive days off. For the last employee. Employe e 1 2 3 4 5 6 7 8 9 OM3 Test Bank Mon Tue Wed Thu Fri Sat 6 5 4 4 3 3 2 1 1 9 8 7 7 6 6 5 4 4 5 5 5 4 4 3 3 2 1 7 7 7 6 6 5 5 4 3 9 8 7 6 5 4 3 3 2 10 9 8 7 6 5 4 4 3 Chapter 14 11 . which days are overstaffed and by how many workers are they overstaffed? ANS: a. ANS: Five employees are needed.5. Monday through Saturday. there are many different options. A young entrepreneur has just opened an electronics store. She estimates the number of employees needed each day as follows: Mon 6 Tue 9 Wed 5 Thu 7 Fri 9 Sat 10 Total 46 a. to 9 p.m. 13 employees are needed. She expects her employees to stock the shelves and also be available for cashier check-out when needed. All employees are full time and work four days in a row with two consecutive days off each week. One of the many tasks that she must address is work scheduling.m. Based on your schedule found in part (a). Numbers underlined are the "circled" days in the algorithm that designate days off. Day: Minimum Personnel Required: M Tu W Th F Sa Su 1 1 3 2 5 4 3 How many employees are needed so that each as two consecutive days off? Construct a work schedule for these employees. M 1 1 1 0 0 Tu 1 1 1 0 0 W 3 2 1 1 0 Th 2 1 0 0 0 F 5 4 3 2 1 Sa 4 3 2 1 0 Su 3 2 1 0 0 (alternate options exist: Su-M) PTS: 1 6. B. Job B. B. D = 59 + 39 = 98 Average waiting time: (30 + 47 + 59 + 98)/4 = 58. the customers are waiting in the lobby for these jobs so the shop wants to minimize the average waiting time. Shortest processing time: Order of jobs: C. Thu. Job D. overstaffed by 1. Wed. a. Average flow time: (12 + 29 + 59 + 98)/4 = 49. What is the averaging waiting (flow) time using their usual first-come first-served rule? ANS: a. In what order should the four jobs be done using the shortest processing time rule? b. C = 47 + 12 = 59. D Completion (flow) times: A = 30. A. A print shop has four jobs that have to be processed through their only five-color press. C. Employe e 1 2 3 4 5 6 7 8 9 10 11 12 13 Total Mon Tue X X X X X X X X X X X X X X X X X 9 X 9 Wed Thu X X X X X X X X X X X X 8 X X X X 8 Fri Sat X X X X X X X X X X X X X X X X X X X X 10 10 PTS: 1 7. 30 minutes. B = 12 + 17 = 29. D Completion (flow) times: C = 12. Job C. A = 29 + 30 = 59. Overstaffed by 1. 12 minutes. They usually use the first-come first-served method of scheduling jobs. overstaffed by 3. B = 30 + 17 = 47. Fri. First-come first-served: Order of jobs: A.50 OM3 Test Bank Chapter 14 12 . 17 minutes. 39 minutes. What is the average waiting (flow) time for all jobs using the shortest processing time rule? c. D = 59 + 39 = 98 b.10 11 12 13 0 0 0 0 3 2 1 1 1 0 0 0 3 2 2 1 1 1 0 0 2 2 1 0 ________ indicates days off b. However. They are going to use the shortest processing time rule to do so.50 c. Processing times for each job are as follows (assume this is the arrival order): Job A. overstaffed by 3. Mon. 7 days a week). A = 2 + 4 = 6. E211. Shortest processing time: Order of jobs: C222. In what order should the planes be repaired using the shortest processing time rule (use first letter of plane)? b. C.0 hours PTS: 1 9. E = 12 + 9 = 21. The repair facility is trying to determine how to schedule the needed repairs. 1 An airplane repair facility has a contract to repair cargo aircraft for a regional airline. F887. Plane A342 B554 C222 D876 E211 F887 Estimated repair time 4 hours 26 hours 2 hours 16 hours 9 hours 6 hours a.PTS: 8. F = 57 + 6 = 63 Average time in shop: (4 + 30 + 32 + 48 + 57 + 63)/6 = 234/6 = 39. B. A342. D876. A print shop has five large commercial printing jobs to finish. What is the average time (in hours) in the shop using the shortest processing time rule? c.5 hours c. F = 6 + 6 = 12. First-come first-served: Order of jobs: A. B554 Completion (flow) times: C = 2. the planes require a considerable amount of maintenance. There are 62 planes in the airline company's fleet of planes. They want to compare the shortest processing time rule and the first-come first-served rule. B = 4 + 26 = 30. only one plane is worked on at a time and the shop is open 24 hours a day. C = 30 + 2 = 32. B = 37 + 26 = 63 b. the following planes need repair and are in the repair facility (data given is in order of plane arrival. Because of the punishing workload. D. What is the average time (in hours) in the shop using the first-come first-served rule? ANS: a. D = 32 + 16 = 48. D = 21 + 16 = 37. They are trying to decide whether to use the shortest processing time (SPT) or the first-come first-served (FCFS) sequencing rule. Data on estimated processing time (in hours) and time to promised completion (in hours) is as follows (jobs shown in order of arrival): Jo b Processing time OM3 Test Bank Time to promised completion Chapter 14 13 . Currently. E = 48 + 9 = 57. Average time in shop: (2 + 6 + 12 + 21 + 37 + 63)/6 = 141/6 = 23. F Completion (flow) times: A 4. E. C = 4 + 5 = 9.A B C D E a.6 hours b. Times for the reports (in hours) are as follows: Projects A B C D E Andrew 4 3 5 7 8 Julie 2 5 1 3 6 a. It is late Friday evening and to their surprise. c. E Completion (flow) times: A = 4. Shortest processing time: Order of jobs: A. 4 9 5 8 11 8 30 17 8 12 What is the average flow time in hours using the FCFS rule? What is the average job lateness in hours using the FCFS rule? What is the average flow time in hours using the SPT rule? What is the average job lateness in hours using the SPT rule? ANS: a. They split the work as follows: Andrew will write and edit the reports while Julie collates data and draws all the necessary graphs. How many hours will it take them to finish all the reports? OM3 Test Bank Chapter 14 14 . E = 26 + 11 = 37 Average flow time: (4 + 13 + 18 + 26 + 37)/5 = 98/5 = 19. The team leaders. d. D = 18 + 8 = 26. so they can finish the reports before Monday morning. Assume that Julie starts her work on a report as soon as Andrew is finished with it and that Andrew works continuously. E = 26 + 11 = 37 Average flow time: (4 + 9 + 17 + 26 + 37)/5 = 18. C. submit the reports to the R&D director on the first Monday of each month. B. Average job lateness (difference between flow time and time to completion): (0 + 0 + 1 + 18 + 25)/5 = 44/5 = 8. They have decided to come to work early Saturday morning. At the end of each month. B = 4 + 9 = 13. C = 13 + 5 = 18. they have discovered that the month ends on Sunday and the reports are due on Monday morning. b. B. Average job lateness (difference between flow time and time to completion): (0 + 0 + 9 + 0 + 25)/5 = 34/5 = 6. Andrew and Julie. C. D.8 hours PTS: 1 10. a research and development team writes status reports for the projects worked on during the month. B = 17 + 9 = 26. E Completion (flow) times: A = 4. D.6 hours d. D = 9 + 8 = 17. What is the order of the projects using Johnson's rule? b. First-come first-served: Order of jobs: A.8 hours c. 07). Work Center I 2. c. A. d. F.62 1.85).58 1. How many hours is Andrew idle? d.71 5. C (27) Julie: B (8).83 hours to complete all tasks c. Work center II idle time: 1. Assume work center I works continuously and that they are using Johnson's rule.24). D (18). F (21.38 5.33). E. A (10. How many hours is Julie idle? ANS: a. E(17).47 5. b. E (18. F (24. Work center I: B (1. Julie idle time: 3 + 3 + 1 + 1 + 3 = 11 hours PTS: 1 11.62).11 What is the sequence of tasks? What is the time in hours to complete all the tasks in both work centers? What is the total idle time in hours for work center I? What is the total idle time in hours for work center II? ANS: a. A (4. D. Work center I idle time: 25. E(11).96 = 1.00). G b. Job order using Johnson's rule: B.66 2.66 hours (wait for task B) OM3 Test Bank Chapter 14 15 . Work centers need not change over to new jobs at the same time.99 7. C. C (10. E.87 hours d.72). D (21).66).52 3. A (24). C (28) (time in parentheses is cumulative hours to complete) It will take 28 hours to complete all of the reports c. Andrew: B (3). Order of jobs using Johnson's rule: B. C (21. G (25. C b. D.c.73 1. A.96) Work center II: B (7. Data appears below in hours: Task A B C D E F G a.50).84 2. A company is faced with seven tasks that have to be processed through two work centers.89 Work Center II 3.83  23.59).99). Andrew idle time: 28  27 = 1 hour d.41 1. G (23. D (22.22 2.83) (time in parentheses is cumulative hours to complete) It will take 25. work center I and then center II.97). D (15. A (22). E (7.