Question 1

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 prioritizes jobs based on the ratio of time until the due date to the processing time, which makes it a good choice for minimizing tardiness and meeting due dates.

Question 2

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 the sequencing of jobs that must pass through two workstations in a fixed sequence. It takes into account both the processing time and the time required for each job to move between the two workstations, providing an optimal sequencing solution. The other sequencing rules listed do not take into account the unique constraints of two workstations with a fixed sequence.

Question 3

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 options are limitations of rules-based dispatching systems. Rules-based systems require regular updates to ensure they are optimized for current conditions, and they may not be able to account for idle or bottleneck resources, or accurately prioritize jobs with identical due dates.

Question 4

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? 
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 5

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. 
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...

Question 6

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 complete time required to complete an order, including the time spent in processing and waiting.

Question 7

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? 
A) R
B) S
C) T
D) U
E) V

Accepted Answer

Johnson's rule involves finding the shortest processing time for each job by looking at the time required at both work centers and scheduling jobs in order of increasing time. For job D, the shortest processing time is 16 minutes (10 minutes at Alpha and 6 minutes at Beta), which is the smallest value among all jobs. Therefore, job D should be scheduled first in the sequence according to Johnson's rule.

Question 8

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 dispatching rule tends to minimize job flow time as it prioritizes the jobs with the shortest processing time, which reduces the overall time for all jobs to complete. FCFS, EDD, LPT, and FCLS dispatching rules do not necessarily minimize job flow time.

Question 9

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 10

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

Question 11

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 12

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 is calculated as (time until due date)/(time until completion). A critical ratio value less than 1 indicates that a job is already late.

Question 13

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? 
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 answer of Five jobs are waiting to be processed....

Question 14

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 (first-come, first-served) dispatching rule seems fair to customers, as it treats all customers equally and in the order in which they arrived. However, it does not necessarily minimize the average number of jobs in the system or the average lateness of all jobs, nor does it maximize the number of jobs completed on time. Therefore, the advantage of FCFS rule is fairness rather than operational efficiency.

Question 15

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? 
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

To apply Johnson's rule, we need to first calculate the "completion time" for each job at each work center by adding up the processing times.

Job | Work Center Sigma | Work Center Delta | Total Completion Time
--- | --- | --- | ---
R | 3 | 7 | 10
S | 9 | 6 | 15
T | 6 | 8 | 14
U | 2 | 5 | 7
V | 5 | 4 | 9

Next, we need to identify the shortest total completion times at both work centers. For work center Sigma, the shortest times are U and R (both take 2 minutes). For work center Delta, the shortest times are V and R (both take 4 minutes). Since R appears in both lists, it must be the first and last job in the sequence (as it requires both work centers).

Next, we can compare U and V to see which comes first in the sequence. U has a total completion time of 7 and V has a total completion time of 9, so U comes before V.

Finally, we need to choose between S and T to come in third in the sequence. S has a total completion time of 15 and T has a total completion time of 14, so T comes before S.

Therefore, the optimal sequence is: R-U-T-V-S.

Question 16

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 sequencing rule is the most appropriate choice for dynamically tracking the progress of jobs and establishing relative priority on a common basis. This rule takes into account both the estimated completion time and the remaining time until the job's due date, allowing for a more accurate assessment of which job is the most pressing to complete next. Using this rule can help ensure that jobs are completed in a timely manner and in the order that makes the most sense for the overall project or production process.

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

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 to solve dynamic scheduling problems while taking into consideration the limited capacity of resources such as labor and machinery. Forward scheduling simply schedules tasks as soon as possible, while backward scheduling schedules tasks to be completed by a certain due date. Infinite scheduling assumes there are infinite resources available, while progressive scheduling is not a commonly used scheduling method.

Question 19

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 20

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 (time a job spends in the system) divided by the number of jobs. Option A is the average processing time per job, but does not take into account any wait or queue time. Option B is the flow time ratio, but includes processing time and wait time. Option D and E include late time, which is not necessary for calculating average completion time. Therefore, option C is the best choice as it considers only the flow time and number of jobs.

Quiz 15: Short-Term Scheduling

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

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.

Flow time represents the time

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?

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

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 .

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

Use of the shortest processing time sequencing rule generally results in

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

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?

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

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 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

Sequencing (or dispatching)

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