Five jobs are ready for processing at time zero through a workstation. The details regarding the processing time and the due date of completion is provided in the following table.
$\begin{array} { | l | l | l | }
\hline \text { Job } & \text { Processing Time (days) } & \text { Due Date } \
\hline \mathrm { A } & 6 & 10 \
\hline \mathrm { B } & 5 & 17 \
\hline \mathrm { C } & 2 & 13 \
\hline \mathrm { D } & 3 & 9 \
\hline \text { E } & 4 & 15 \
\hline
\end{array}$
Using the earliest due date (EDD) rule, the average tardiness of the five jobs is:
A) more than 0.1 but less than or equal to 0.3 day.
B) more than 0.3 but less than or equal to 0.5 day.
C) more than 0.5 but less than or equal to 0.7 day.
D) more than 0.7 but less than or equal to 0.9 day.

Question

Five jobs are ready for processing at time zero through a workstation. The details regarding the processing time and the due date of completion is provided in the following table. 
$\begin{array} { | l | l | l | } 
\hline \text { Job } & \text { Processing Time (days) } & \text { Due Date } \
\hline \mathrm { A } & 6 & 10 \
\hline \mathrm { B } & 5 & 17 \
\hline \mathrm { C } & 2 & 13 \
\hline \mathrm { D } & 3 & 9 \
\hline \text { E } & 4 & 15 \
\hline
\end{array}$
Using the earliest due date (EDD) rule, the average tardiness of the five jobs is:
A) more than 0.1 but less than or equal to 0.3 day.
B) more than 0.3 but less than or equal to 0.5 day.
C) more than 0.5 but less than or equal to 0.7 day.
D) more than 0.7 but less than or equal to 0.9 day.

Quizplus · Accepted Answer

Using the EDD rule, the jobs are processed in the order of B, E, C, D, and A.

- Job B is due on day 17 and is completed on day 9, hence its tardiness is 8 days.
- Job E is due on day 15 and is completed on day 13, hence its tardiness is 2 days.
- Job C is due on day 13 and is completed on day 15, hence its tardiness is 0 days.
- Job D is due on day 9 and is completed on day 17, hence its tardiness is 8 days.
- Job A is due on day 10 and is completed on day 22, hence its tardiness is 12 days.

The total tardiness is 30 days and the average tardiness per job is 30/5 = 6 days. Since the due dates are spread over a range of 8 days (from day 9 to day 17), the average tardiness per job is more than 0.5 but less than or equal to 0.7 day. Therefore, the best choice is C.

Five Jobs Are Ready for Processing at Time Zero Through