The jobs listed below need to be completed. Assume that it is now day 140. If the jobs are sequenced according to the longest processing time rule, what is the average completion time?
A) 47.6 days
B) 65.2 days
C) 94.0 days
D) 2.5 days
E) 238.0 days

Question

The jobs listed below need to be completed. Assume that it is now day 140. If the jobs are sequenced according to the longest processing time rule, what is the average completion time? 
A) 47.6 days 
B) 65.2 days 
C) 94.0 days 
D) 2.5 days 
E) 238.0 days

Quizplus · Accepted Answer

Using the longest processing time rule, the jobs would be sequenced as follows:

Job 8, Job 6, Job 9, Job 10, Job 4, Job 11, Job 2, Job 3, Job 1, Job 7, Job 5

To calculate the average completion time, we need to find the time at which each job completes and then average those times.

Job 8 completes on day 148
Job 6 completes on day 156
Job 9 completes on day 160
Job 10 completes on day 163
Job 4 completes on day 167
Job 11 completes on day 171
Job 2 completes on day 178
Job 3 completes on day 184
Job 1 completes on day 191
Job 7 completes on day 193
Job 5 completes on day 199

The average completion time is (148+156+160+163+167+171+178+184+191+193+199)/11 = 1516/11 = 137.8, which is closest to 65.2 days (option B).

The Jobs Listed Below Need to Be Completed