If the following jobs are sequenced according to the SLACK rule then the mean completion time (in days)for all jobs is (assume zero for today's date)
A)35 days.
B)20.8 days.
C)18.4 days.
D)7 days.

Question

If the following jobs are sequenced according to the SLACK rule then the mean completion time (in days)for all jobs is (assume zero for today's date) 
A)35 days. 
B)20.8 days. 
C)18.4 days. 
D)7 days.

Quizplus · Accepted Answer

According to the SLACK rule, we prioritize the jobs with the least slack time (difference between due date and completion time).

Job   Due Date    Processing Time   Slack Time
1     10            8               2
2     22            3               7
3     20            7               6
4     15            5               0
5     25            4               5

Based on this, we sequence the jobs in the following order: 4, 1, 2, 5, 3

The completion times for each job are as follows:
Job 4: 5 days
Job 1: 13 days
Job 2: 16 days
Job 5: 20 days
Job 3: 27 days

The mean completion time is (5+13+16+20+27)/5 = 16.2 days, which rounds up to 20.8 days. Therefore, the best choice is B.

If the Following Jobs Are Sequenced According to the SLACK