Deck 14: Operations Scheduling and Sequencing

Question 1

Scheduling problems occur almost exclusively in manufacturing.

Answer 1

False

Question 2

Scheduling refers to determining the order in which jobs or tasks are processed.

Answer 2

False

Question 3

For a single processor, a first-come, first-served (FCFS) rule minimizes the average flow time because customer waiting time will be minimized.

Answer 3

False

Question 4

The makespan is the sum of flow times of a given set of jobs.

Question 5

The EDD rule minimizes the maximum of jobs past due but doesn't perform well on average flow-time, WIP inventory or resource utilization.

Question 6

In sequencing a set of jobs on a single processor, different sequences will have different makespans but the same average flow times.

Question 7

The shortest processing time rule and earliest due date rule will always provide the same sequence.

Question 8

A lateness measure can only be 0 or a positive number.

Question 9

Telling an umpire crew to work baseball games in Chicago, then Milwaukee, and then Cleveland is an example of a sequence.

Question 10

The SPT sequencing rule will maximize the average flow time.

Question 11

Flow time is the amount of time a job spends in a shop or factory.

Question 12

In practice, whenever processing times of a set of jobs are about equal, managers typically use a first-come, first-serve rule.

Question 13

A tardiness measure can be either zero (0) or a positive number.

Question 14

Indirectly, appointments reduce the cost of providing a service because the service provider is idle less each workday.

Question 15

High flow times reduce WIP inventory.

Question 16

Sequencing is not as much of a concern when several activities use a common resource.

Question 17

Tardiness measures the amount of time by which the completion time exceeds the due date.

Question 18

Since all jobs eventually get done, job sequencing has no effect on resource utilization.

Question 19

Appointments can be viewed as a reservation of service time and capacity.

Question 20

Scheduling and sequencing methods used in manufacturing are more beneficial in low-contact, than high-contact, service processes.

Question 21

Considering a two-resource sequencing problem,

A)The makespan is the same for any sequence of jobs
B)Flow time is minimized
C)The goal is to minimize makespan
D)Each job can be processed by either resource first

Question 22

The time to rest and travel between games for baseball umpire crews is an important factor in developing their schedule.

Question 23

The sequencing rule that minimizes the maximum number of jobs that are past due from a given set of jobs is

A)Shortest processing time
B)Earliest due date
C)First come, first served
D)Least work remaining

Question 24

The Shortest Processing Time (SPT) rule

A)Ensures that due dates are met
B)Maximizes average flow-time
C)Minimizes resource utilization
D)Minimizes work in process inventory

Question 25

In sequencing jobs in a flow shop with two resources, Johnson's rule finds a sequence that has the smallest makespan.

Question 26

The numerical difference between the completion time and the due date is called

A)Flow time
B)Lateness
C)Makespan
D)Tardiness

Question 27

When several products share common facilities, product sequencing affects cost.

Question 28

Triage by nurses in an emergency room would be an example of

A)Scheduling
B)Sequencing
C)Appointments
D)Shortest-processing-time rule

Question 29

Which of the following is not a consideration when designing an appointment system?

A)Determining the appointment time interval
B)Determining the appropriate sequencing rule
C)Determining the length of each workday and the time off-duty
D)Deciding on an overbooking policy

Question 30

Scheduling applies to all aspects of the value chain.

Question 31

Gantt charts can show what jobs are ahead of schedule, behind schedule, and on schedule.

Question 32

If the highest priority is to minimize the average job lateness, then the jobs sequence should begin with those jobs requiring

A)The shortest processing time
B)The smallest critical ratio
C)The least remaining operations
D)The longest processing time

Question 33

Staff scheduling needs all of the following except

A)Flow-time estimates
B)Accurate forecasting
C)Staffing levels required by time period
D)Determining available personnel

Question 34

Two examples of process-focused performance measures for sequencing rules are flow time and lateness.

Question 35

Rescheduling rarely occurs unless customers change their requested due dates.

Question 36

Scheduling refers to specifying

A)The sequence that jobs must be completed
B)The due date for each job
C)The start and completion times of jobs
D)The makespan of each job

Question 37

The time needed to process a given set of jobs is called

A)Flow time
B)Ready time
C)Makespan
D)Due date

Question 38

Appointments systems often overbook to maximize revenue.

Question 39

UPS, the world's largest package delivery company, is highly dependent on scheduling but not sequencing.

Question 40

Like the SPT rule, the earliest due date (EDD) rule minimizes the average flow time.

Question 41

Explain why any sequence chosen in the single-machine scheduling problem will not change makespan time.

Question 42

What four (4) decisions are considered in designing an appointment system?

Question 43

Johnson's sequencing rule is used to sequence

A)several jobs through several work centers
B)several jobs through one work center
C)two jobs through several work centers
D)several jobs through two work centers

Question 44

Compare and contrast the advantages and disadvantages of the Shortest Processing Time (SPT) and the Earliest Due Date (EDD) sequencing rules.

Question 45

A movie theater requires the following minimum number of employees, each of which is required to have two consecutive days off. How many employees are needed so that each as two consecutive days off? Construct a work schedule for these employees.

Question 46

Staff scheduling attempts to match available personnel with the needs of the organization by performing what four steps?

Question 47

The table below includes processing times and due dates for five jobs.

a.Use the Shortest Processing Time Rule (SPT) to determine the average flow time.
b.Use the Earliest Due Date Rule (EDD) to determine the average lateness.

Question 48

Short-term capacity fluctuations necessitate changes in schedules.List at least five factors affecting short-term capacity.

Question 49

Which of the following is NOT a criterion for evaluating job sequencing rules?

A)average flow time
B)lateness
C)tardiness
D)sum of processing times

Question 50

Which of the following is an example of a situation for which a Gantt chart would be appropriate?

A)developing a factory layout
B)tracking inventory levels over time
C)monitoring job schedules
D)forecasting personnel requirements in a two-shift operation

Question 51

A requirement of Johnson's two-resource sequencing rule is

A)All jobs must begin at the same time
B)Jobs must be processed through each work center in the same job sequence
C)Only two jobs can be processed at a time through each work center
D)Total processing time must be minimized

Question 52

The chief disadvantage of the shortest processing time rule is:

A)average job completion times are excessive
B)average number of jobs in the system is excessive
C)long-duration jobs may have excessive completion times
D)average job lateness is excessive

Question 53

Describe Johnson's sequencing rule for the two-resource sequencing problem.

Question 54

Differentiate between scheduling and sequencing.

Question 55

A new surgical facility called Cut & Sew is opening in neighborhoods throughout the United States.They are job shops that handle a variety of outpatient surgical procedures.Their process is set up so that one doctor cuts and the other sews.They have five patients to sequence for tomorrow.Since the weather forecast is for a cool and sunny day, they would also like to play golf tomorrow.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.The patients and estimated times are as follows:
Sequence the patients using Johnson's Method, state the schedule for each operation, and determine the minimum makespan.

Question 56

Explain the three categories of criteria used to evaluate job sequencing performance.For each category, provide two example measures.

Question 57

A restaurant needs the following number of wait staff to serve its evening guests.
How many employees are needed so that each as two consecutive days off? Construct a work schedule for these employees.

Question 58

Give at least five examples of service organizations (and employee type) where, due to high variability in customer demand, staff scheduling problems are prevalent.

Question 59

The following five jobs, along with their processing time and due dates, are given below.

a.Use the Shortest Processing Time Rule (SPT) and determine the average flow-time for the five jobs
b.Use the Earliest Due Date Rule (EDD) and determine the average lateness and tardiness.

Question 60

ScheduleAnywhere.com on-line software helps clients do all the following except

A)Schedule employees from any computer with Internet access.
B)Decide how much to overbook for each day of the week.
C)See who's scheduled and who's available.
D)Avoid scheduling conflicts.

Question 61

An airplane repair facility has a contract to repair cargo aircraft for a regional airline.There are 62 planes in the airline company's fleet of planes.Because of the punishing workload, the planes require a considerable amount of maintenance.The repair facility is trying to determine how to schedule the needed repairs.They want to compare the shortest processing time rule and the first-come first-served rule.Currently, the following planes need repair and are in the repair facility (data given is in order of plane arrival, only one plane is worked on at a time and the shop is open 24 hours a day, 7 days a week).

a.In what order should the planes be repaired using the shortest processing time rule (use first letter of plane)?
b.What is the average time (in hours) in the shop using the shortest processing time rule?
c.What is the average time (in hours) in the shop using the first?come first?served rule?

Question 62

A print shop has five large commercial printing jobs to finish.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):

a.What is the average flow time in hours using the FCFS rule?
b.What is the average job lateness in hours using the FCFS rule?
c.What is the average flow time in hours using the SPT rule?
d.What is the average job lateness in hours using the SPT rule?

Question 63

A young entrepreneur has just opened an electronics store.One of the many tasks that she must address is work scheduling.She plans to stay open from 9a.m.to 9 p.m.Monday through Saturday.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.She estimates the number of employees needed each day as follows:

a.Use the days-off scheduling procedure to determine the minimum number of employees required?
b.Based on your schedule found in part (a), which days are overstaffed and by how many workers are they overstaffed?

Question 64

At the end of each month, a research and development team writes status reports for the projects worked on during the month.The team leaders, Andrew and Julie, submit the reports to the R&D director on the first Monday of each month.It is late Friday evening and to their surprise, they have discovered that the month ends on Sunday and the reports are due on Monday morning.They have decided to come to work early Saturday morning, so they can finish the reports before Monday morning.They split the work as follows: Andrew will write and edit the reports while Julie collates data and draws all the necessary graphs.Assume that Julie starts her work on a report as soon as Andrew is finished with it and that Andrew works continuously.Times for the reports (in hours) are as follows:

a.What is the order of the projects using Johnson's rule?
b.How many hours will it take them to finish all the reports?
c.How many hours is Andrew idle?
d.How many hours is Julie idle?

Question 65

A print shop has four jobs that have to be processed through their only five-color press.They usually use the first-come first-served method of scheduling jobs.However, the customers are waiting in the lobby for these jobs so the shop wants to minimize the average waiting time.They are going to use the shortest processing time rule to do so.Processing times for each job are as follows (assume this is the arrival order): Job A, 30 minutes; Job B, 17 minutes; Job C, 12 minutes; Job D, 39 minutes.
a.In what order should the four jobs be done using the shortest processing time rule?
b.What is the average waiting (flow) time for all jobs using the shortest processing time rule?
c.What is the averaging waiting (flow) time using their usual first-come first-served rule?

Question 66

A company is faced with seven tasks that have to be processed through two work centers, work center I and then center II.Assume work center I works continuously and that they are using Johnson's rule.Work centers need not change over to new jobs at the same time.Data appears below in hours:

a.What is the sequence of tasks?
b.What is the time in hours to complete all the tasks in both work centers?
c.What is the total idle time in hours for work center I?
d.What is the total idle time in hours for work center II?