Question 1

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 centre 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 is a scheduling system that takes into account work centre capacities and other resource availabilities. This creates a more realistic schedule compared to conventional MRP which ignores capacity issues. Therefore, the best choice is C.

Question 2

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 mentioned options are limitations of rules-based dispatching systems. Rules need to be regularly revised and updated to accommodate changes in orders and product mix. Rules may not be able to recognize idle resources and bottleneck resources. They also may not be able to prioritize two jobs with identical due dates.

Question 3

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 (shortest processing time) tends to minimize job flow time by prioritizing the jobs with the shortest processing time, allowing them to be completed quickly and move on to the next job. This helps to prevent long waiting times for jobs with longer processing times, ultimately reducing job flow time.

Question 4

Sequencing (or dispatching)
A) assigns dates to specific jobs or operations steps.
B) assigns jobs to work centres.
C) specifies the order in which jobs should be done at each centre.
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 5

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 takes into account the remaining processing time and the time until the due date, allowing for a flexible approach to sequencing based on the progress of jobs. This rule ensures that jobs with the highest priority are completed first, while also taking into consideration the time remaining until the due date. Therefore, it is the best choice for dynamically tracking the progress of jobs and establishing relative priority on a common basis.

Question 6

Eight jobs have been sequenced at a single work centre. 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% ; 10.625
B) low; .0941
C) 0.400 or 40%; 2.5
D) 0.235 or 23.5%; 4.25
E) maximized; minimized

Accepted Answer

Utilization can be calculated as total processing time divided by total flow time. 
Utilization = 34/85 = 0.4 or 40%

Average jobs in the system can be calculated as total flow time divided by processing time of each job. 
Average jobs in the system = 85/34 = 2.5

Therefore, the best choice is C, which provides the correct values for utilization and average jobs in the system.

Question 7

Average completion time for a schedule sequence at a work centre 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 calculated as the total flow time divided by the number of jobs. This is because the total flow time measures the time a job spends in the system (i.e. from the moment it enters the work center until it leaves), and dividing by the number of jobs gives us an average time per job. Option A is incorrect because it only takes into account the processing time of each job, but it does not include any waiting or queueing time. Option B is incorrect because it divides the total flow time by the total processing time, which does not account for any waiting or queueing time either. Option D and E are incorrect because they add the total late time (i.e. time a job spends beyond its due date) to the numerator, which is not necessary to calculate the average completion time per job. Therefore, the best choice is C.

Question 8

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

FCFS dispatching rule gives an impression of fairness to customers, as the customers who arrive first are served first. However, FCFS has disadvantages in terms of average number of jobs in the system, average lateness, and number of jobs completed on time. Therefore, the advantage of FCFS in services is that it seems fair to customers.

Question 9

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 designed to minimize the average time it takes for jobs to flow through the system, which directly contributes to minimizing average flow time. Additionally, by efficiently scheduling jobs based on their processing times, it can lead to maximum utilization of resources, as shorter jobs are completed quickly and resources are continuously employed.

Question 10

Five jobs are waiting for processing through two work centres. Their processing time (in minutes) at each work centre is contained in the table below. Each job requires work centre Alpha before work centre 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) V-U-T-S-R; 250

Accepted Answer

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

Question 11

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) E, C, B, D, A

Accepted Answer

The earliest due date dispatching rule prioritizes jobs based on their due dates, from earliest to latest. The order is B (due in 4 days), D (due in 5 days), A (due in 7 days), E (due in 8 days), and C (due in 11 days).

Question 12

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 takes into account the due date of the job and the processing time to determine which jobs should be prioritized. This rule is often considered the most effective method for scheduling jobs as it prioritizes those jobs that are closest to their due date and require less processing time.

Question 13

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

When jobs must pass through two workstations in a fixed sequence, Johnson's rule is the most commonly applied sequencing rule. This is because Johnson's rule is specifically designed for two-stage processes and efficiently minimizes the total processing time by prioritizing the order in which jobs are processed through each stage.

Question 14

Five jobs are waiting for processing through two work centres. Their processing time (in minutes) at each work centre is contained in the table below. Each job requires work centre Sigma before work centre 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 15

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) A, B, C, D, E

Accepted Answer

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

Question 16

Which critical ratio value implies that a job is already late?
A) more than 100
B) 1
C) less than 1
D) 10
E) 110

Accepted Answer

The critical ratio is calculated by dividing the time remaining until the due date by the time required to complete the job. If the critical ratio is less than 1, the job is already late. Therefore, choice C is the correct option.

Question 17

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 18

Flow time represents the time
A) an order spends waiting for processing at a work centre.
B) an order spends being processed at a work centre.
C) an order spends moving from one work centre to another.
D) to complete an order, including time spent in processing and in waiting.
E) an order spends moving from a work centre to storage.

Accepted Answer

Flow time is the total time taken by an order to complete its entire process, including the time spent in processing and waiting. Option A refers to waiting time only, while option B refers to processing time only. Option C and E refer to movement time only, which is not the same as flow time. Therefore, option D is the best choice as it sums up the entire time taken for an order to complete its process.

Question 19

Five jobs are waiting for processing through two work centres. Their processing time (in minutes) at each work centre is contained in the table below. Each job requires work centre Alpha before work centre 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 selecting the job with the shortest processing time at either work center and scheduling it either as early as possible if that time is in the first work center (Alpha) or as late as possible if that time is in the second work center (Beta). In this case, Job U has the shortest processing time in the first work center (Alpha) with 15 minutes, so it should be scheduled first.

Question 20

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 uses expert systems and simulation to solve dynamic scheduling problems by taking into account the finite capacity of resources available for production. This allows for more accurate scheduling and less disruption in production processes.

Quiz 15: Short-Term Scheduling

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 centre capacities and other resource availabilities is

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

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

Sequencing (or dispatching)

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

Eight jobs have been sequenced at a single work centre. 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 .

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

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

Use of the shortest processing time sequencing rule generally results in

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

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

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

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

Flow time represents the time

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