Question 1

Use of the shortest processing time sequencing rule generally results in
A) maximum average lateness
B) maximum utilization
C) maximum effectiveness
D) minimum average flow time
E) B and D

Accepted Answer

The shortest processing time sequencing rule is known for minimizing the average flow time of jobs through a system, which in turn can lead to higher utilization of resources as jobs are completed more efficiently.

Question 2

Flow time represents the time
A) an order spends waiting for processing at a work center
B) an order spends being processed at a work center
C) an order spends moving from one work center to another
D) to complete an order, including time spent in processing and in waiting
E) none of the above

Accepted Answer

Flow time represents the total time taken by an order to complete, including the time spent in processing and waiting at work centers. It considers the entire process of completing an order, from its arrival until its fulfillment. Therefore, option D is the best choice.

Question 3

Which of the following dispatching rules is typically the best technique for taking first those jobs with the most urgent needs?
A) shortest processing time
B) critical ratio
C) earliest due date
D) longest processing time
E) none of the above

Accepted Answer

The answer of Which of the following dispatching rules is...

Question 4

A recent advance in short-term scheduling that makes use of expert systems and simulation in solving dynamic scheduling problems is
A) forward scheduling
B) backward scheduling
C) infinite scheduling
D) finite capacity scheduling
E) progressive scheduling

Accepted Answer

Finite capacity scheduling makes use of expert systems and simulation in solving dynamic scheduling problems. This type of scheduling takes into account the capacity of resources available, such as the number of machines or workers, and uses algorithms and heuristics to schedule tasks based on the availability of those resources. This approach allows for more efficient allocation of resources and can help reduce the risk of overloading or underutilizing resources.

Question 5

Five jobs are waiting for processing through two work centers. Their processing time (in minutes) at each work center is contained in the table below. Each job requires work center Alpha before work center Beta. According to Johnson's rule, what is the optimum sequence of jobs and the minimum time for completion of all jobs?
$$\begin{array} { | c | c | c | } 
\hline \text { Job } & \text { Alpha } & \text { Beta } \
\hline R & 20 & 10 \
\hline \mathrm { S } & 25 & 35 \
\hline \mathrm { T } & 50 & 20 \
\hline \mathrm { U } & 15 & 35 \
\hline \mathrm { V } & 55 & 75 \
\hline
\end{array}$$
A) V-T-S-U-R; 225
B) U-R-T-S-V; 175
C) R-S-T-U-V; 240
D) U-S-V-T-R; 200
E) none of the above

Accepted Answer

The answer of Five jobs are waiting for processing through...

Question 6

Which of the following are limitations of rules-based dispatching systems?
A) Rules need to be revised to adjust to changes in orders, product mix, and so forth.
B) Rules may not recognize idle resources.
C) Rules may not recognize bottleneck resources
D) Rules may not be able to prioritize two jobs with identical due dates.
E) All of the above are limitations.

Accepted Answer

All of the above are limitations of rules-based dispatching systems. Rules may need to be constantly revised to adjust to changes in orders, product mix, and other variables. Additionally, rules may not recognize idle or bottleneck resources, and may not be able to prioritize between jobs with identical due dates.

Question 7

Five jobs are waiting to be processed. Their processing times and due dates are given below. Using the earliest due date dispatching rule, in which order should the jobs be processed?
$$\begin{array} { | c | c | c | } 
\hline \text { Job } & \begin{array} { c } 
\text { Processing } \
\text { Time (days) }
\end{array} & \begin{array} { c } 
\text { Job due date } \
\text { (days) }
\end{array} \
\hline \text { A } & 4 & 7 \
\hline \text { B } & 2 & 4 \
\hline \text { C } & 8 & 11 \
\hline \text { D } & 3 & 5 \
\hline \text { E } & 5 & 8 \
\hline
\end{array}$$
A) C, E, A, D, B
B) A, B, C, D, E
C) B, D, A, E, C
D) C, B, A, E, D
E) none of the above

Accepted Answer

The earliest due date rule schedules jobs in order of their due dates. The order based on due dates is: B (4), D (5), A (7), E (8), C (11).

Question 8

Eight jobs have been sequenced at a single work center. Total processing time for the eight jobs is 34 hours and total flow time for the sequence is 85 hours. For this schedule, utilization is __________ and average jobs in the system is __________.
A) 100 percent; 10.625
B) low; .0941
C) 0.400 or 40 percent; 2.5
D) 0.235 or 23.5 percent; 4.25
E) maximized; minimized

Accepted Answer

Utilization = processing time / flow time = 34 / 85 = 0.4 or 40%
Average jobs in the system = flow time / processing time = 85 / 34 = 2.5

Question 9

Which of the following is an advantage of the FCFS dispatching rule when used in services?
A) FCFS is easy to update.
B) FCFS minimizes the average number of jobs in the system.
C) FCFS minimizes the average lateness of all jobs.
D) FCFS maximizes the number of jobs completed on time.
E) FCFS seems fair to customers.

Accepted Answer

The FCFS dispatching rule in services is advantageous because it appears fair to customers. Customers tend to get served in the order in which they arrived, which creates a perception of fairness. However, FCFS does not necessarily minimize the average number of jobs in the system, the average lateness of all jobs, or maximize the number of jobs completed on time. Therefore, option A, B, C, and D are incorrect.

Question 10

Five jobs are waiting for processing through two work centers. Their processing time (in minutes) at each work center is contained in the table below. Each job requires work center Sigma before work center Delta. According to Johnson's rule, what sequence of jobs will minimize the completion time for all jobs?
$$\begin{array} { | c | c | c | } 
\hline \text { Job } & \text { Sigma } & \text { Delta } \
\hline R & 40 & 10 \
\hline \mathrm { S } & 25 & 30 \
\hline \mathrm { T } & 50 & 20 \
\hline \mathrm { U } & 35 & 35 \
\hline \mathrm { V } & 55 & 15 \
\hline
\end{array}$$
A) R-S-T-U-V
B) S-V-T-R-U
C) S-U-T-V-R
D) V-R-U-S-T
E) none of the above

Accepted Answer

The answer of Five jobs are waiting for processing through...

Question 11

The priority rule that sequences jobs using the smallest ratio of due date from today to processing time is
A) critical ratio
B) earliest due date
C) first come, first served
D) longest processing time
E) shortest processing time

Accepted Answer

The critical ratio rule is considered one of the best priority rules for scheduling because it takes both the due date and processing time into account. It is calculated by dividing the time between today and the due date by the processing time. The resulting ratio represents the urgency of the job and helps to prioritize the jobs accordingly. The smaller the ratio, the higher the urgency, and higher priority the job receives. Therefore, A) Critical Ratio is the best choice for sequencing jobs using the smallest ratio of due date from today to processing time.

Question 12

Sequencing (or dispatching)
A) assigns dates to specific jobs or operations steps
B) assigns jobs to work centers
C) specifies the order in which jobs should be done at each center
D) assigns workers to jobs
E) assigns workers to machines

Accepted Answer

Sequencing specifies the order in which jobs should be done at each center.

Question 13

Average completion time for a schedule sequence at a work center is the ratio of
A) total processing time to the number of jobs
B) total flow time to total processing time
C) total flow time to the number of jobs
D) total processing time plus total late time to the number of jobs
E) total flow time plus total late time to the number of jobs

Accepted Answer

The average completion time for a schedule sequence at a work center is the total flow time divided by the number of jobs. Total flow time is the sum of processing time and waiting time, and since there is no information given about waiting time, we cannot calculate option B. Option A only considers processing time, ignoring waiting time altogether. Option D includes late time which is not relevant to finding average completion time. Option E includes both late time and flow time, which exaggerates the average completion time, making it less accurate. Therefore, option C is the best choice as it only considers total flow time which is essential to finding the average completion time.

Question 14

Which critical ratio value implies that a job is already late?
A) more than 100
B) 1
C) less than 1
D) 10
E) none of the above

Accepted Answer

The critical ratio (CR) is calculated by dividing the time remaining until a job’s deadline by the time required to complete the job. A critical ratio less than 1 indicates that the job is already late, while a ratio greater than 1 indicates that the job can still be completed before the deadline. Therefore, choice C (less than 1) implies that a job is already late.

Question 15

The most appropriate sequencing rule to use if the goal is to dynamically track the progress of jobs and establish relative priority on a common basis is
A) shortest processing time
B) earliest due date
C) critical ratio
D) longest processing time
E) Johnson's rule

Accepted Answer

The critical ratio rule considers both the job's remaining processing time and its remaining time until the due date. This allows for the dynamic tracking of job progress and establishes relative priority based on a common basis. It balances the urgency of completing a job with the amount of work remaining, resulting in a more effective scheduling approach. Other rules such as shortest processing time or longest processing time do not consider due dates, and earliest due date may not take into account job progress. Johnson's rule is primarily used for two-machine sequencing.

Question 16

Five jobs are waiting for processing through two work centers. Their processing time (in minutes) at each work center is contained in the table below. Each job requires work center Alpha before work center Beta. According to Johnson's rule, which job should be scheduled first in the sequence?
$$\begin{array} { | c | c | c | } 
\hline \text { Job } & \text { Alpha } & \text { Beta } \
\hline R & 20 & 10 \
\hline \mathrm { S } & 25 & 35 \
\hline \mathrm { T } & 50 & 20 \
\hline \mathrm { U } & 15 & 35 \
\hline \mathrm { V } & 55 & 75 \
\hline
\end{array}$$
A) R
B) S
C) T
D) U
E) V

Accepted Answer

Johnson's rule for scheduling jobs through two work centers involves arranging jobs in order of increasing processing time, where the shortest processing time at either work center determines the sequence. The job with the shortest processing time in either work center goes first. Job U has the shortest processing time in work center Alpha (15 minutes), making it the first job to be scheduled according to Johnson's rule.

Question 17

Which of the following dispatching rules tends to minimize job flow time?
A) FCFS: first come, first served
B) SPT: shortest processing time
C) EDD: earliest due date
D) LPT: longest processing time
E) FCLS: first come, last served

Accepted Answer

SPT rule tends to minimize job flow time by prioritizing shorter jobs, which reduces the average waiting time of all jobs in the system.

Question 18

When a set of jobs must pass through two workstations whose sequence is fixed, __________ is the sequencing rule most commonly applied.
A) critical ratio
B) earliest due date
C) first come, first served
D) slack time remaining
E) Johnson's rule

Accepted Answer

Johnson's rule is specifically designed for situations where a set of jobs must pass through two workstations whose sequence is fixed. It determines the optimal sequencing of jobs based on their processing times at each workstation, ensuring that the overall processing time is minimized. The other sequencing rules listed are not as well-suited to this specific scenario.

Question 19

Conventional MRP uses time buckets that do not recognize capacity limits, and in fact ignores capacity issues. A more realistic scheduling system that includes work center capacities and other resource availabilities is
A) aggregate planning
B) the master production schedule
C) finite capacity scheduling
D) the assignment method
E) level material use

Accepted Answer

Finite capacity scheduling recognizes the capacity limits of work centers and other resource availabilities. It uses this information to generate a more realistic schedule based on the availability of resources, taking into account other constraints such as material availability, setup times, and labor requirements. The other options listed do not specifically address capacity limitations in the same way.

Question 20

Five welding jobs are waiting to be processed. Their processing times and due dates are given below. Using the critical ratio dispatching rule, in which order should the jobs be processed? All dates are specified as days from Today.
$$\begin{array} { | c | c | c | } 
\hline \text { Job } & \begin{array} { c } 
\text { Processing } \
\text { Time (days) }
\end{array} & \begin{array} { c } 
\text { Job due date } \
\text { (days) }
\end{array} \
\hline \text { A } & 4 & 7 \
\hline \text { B } & 2 & 4 \
\hline \text { C } & 8 & 11 \
\hline \text { D } & 3 & 5 \
\hline \text { E } & 5 & 11 \
\hline
\end{array}$$
A) B, D, A, E, C
B) C, D, A, B, E
C) C, E, A, D, B
D) E, B, A, D, C
E) none of the above

Accepted Answer

The answer of Five welding jobs are waiting to be...

Quiz 18: Short-Term Scheduling

Use of the shortest processing time sequencing rule generally results in

Flow time represents the time

Which of the following dispatching rules is typically the best technique for taking first those jobs with the most urgent needs?

A recent advance in short-term scheduling that makes use of expert systems and simulation in solving dynamic scheduling problems is

Which of the following are limitations of rules-based dispatching systems?

Eight jobs have been sequenced at a single work center. Total processing time for the eight jobs is 34 hours and total flow time for the sequence is 85 hours. For this schedule, utilization is and average jobs in the system is .

Which of the following is an advantage of the FCFS dispatching rule when used in services?

The priority rule that sequences jobs using the smallest ratio of due date from today to processing time is

Sequencing (or dispatching)

Average completion time for a schedule sequence at a work center is the ratio of

Which critical ratio value implies that a job is already late?

The most appropriate sequencing rule to use if the goal is to dynamically track the progress of jobs and establish relative priority on a common basis is

Which of the following dispatching rules tends to minimize job flow time?

When a set of jobs must pass through two workstations whose sequence is fixed, __________ is the sequencing rule most commonly applied.

Conventional MRP uses time buckets that do not recognize capacity limits, and in fact ignores capacity issues. A more realistic scheduling system that includes work center capacities and other resource availabilities is