The owner/operator of the local franchise of Handyman, Inc., has four jobs to do today, shown in the order they were received: $$\begin{array} { l c c }
\text { Job } & \text { Processing } & \text { Due } \
&\text { Time (hrs) } & \text { (hrs from now) } \
\hline \mathrm { W } & 4 & 4 \
\mathrm { X } & 3 & 5 \
\mathrm { Y } & 2 & 2 \
\mathrm { Z } & 1 & 1
\end{array}$$ If he uses the shortest processing time first priority rule to schedule these jobs, what will be the average number of jobs in his shop today?
A) 0
B) 1
C) 2
D) 3
E) 4

Question

The owner/operator of the local franchise of Handyman, Inc., has four jobs to do today, shown in the order they were received: $$\begin{array} { l c c } 
\text { Job } & \text { Processing } & \text { Due } \
&\text { Time (hrs) } & \text { (hrs from now) } \
\hline \mathrm { W } & 4 & 4 \
\mathrm { X } & 3 & 5 \
\mathrm { Y } & 2 & 2 \
\mathrm { Z } & 1 & 1
\end{array}$$ If he uses the shortest processing time first priority rule to schedule these jobs, what will be the average number of jobs in his shop today?
A) 0
B) 1
C) 2
D) 3
E) 4

Quizplus · Accepted Answer

Using the shortest processing time first priority rule, the owner/operator should first do Job Z (which takes 1 hour) and then Job Y (which takes 2 hours). At this point, Job Z will be completed and Job W (which takes 4 hours and is due in 4 hours) will be next in line. The owner/operator can then start Job X (which takes 3 hours) while Job W is being completed. Overall, the four jobs will take 1+2+4+3 = 10 hours to complete. The time between each job completion is 1, 3, and 6 hours. Therefore, at any given time, there will be an average of 2 jobs in the shop (Job Z and either Job Y or Job X). Thus, the answer is C) 2.

The Owner/operator of the Local Franchise of Handyman, Inc If He Uses the Shortest Processing Time First Priority Rule