The average tardiness for the jobs listed in the following table under the FCFS (first come,first served)rule is ______. $$\begin{array} { | c | c | c | }
\hline \text { Job } & \begin{array} { c }
\text { Processing time } \
\text { (in days\} }
\end{array} & \begin{array} { c }
\text { Due date (in days from } \
\text { today's date\} }
\end{array} \
\hline \text { A } & 4 & 9 \
\hline \text { B } & 10 & 18 \
\hline \text { C } & 6 & 6 \
\hline \text { D } & 12 & 19 \
\hline \text { E } & 7 & 17 \
\hline
\end{array}$$
A)11 days
B)9.8 days
C)15 days
D)8 days

Question

The average tardiness for the jobs listed in the following table under the FCFS (first come,first served)rule is ______. $$\begin{array} { | c | c | c | } 
\hline \text { Job } & \begin{array} { c } 
\text { Processing time } \
\text { (in days\} }
\end{array} & \begin{array} { c } 
\text { Due date (in days from } \
\text { today's date\} }
\end{array} \
\hline \text { A } & 4 & 9 \
\hline \text { B } & 10 & 18 \
\hline \text { C } & 6 & 6 \
\hline \text { D } & 12 & 19 \
\hline \text { E } & 7 & 17 \
\hline
\end{array}$$
A)11 days
B)9.8 days
C)15 days
D)8 days

Quizplus · Accepted Answer

To calculate tardiness, we subtract the due date from the completion date. For FCFS, we just need to add up the processing times in the order they are given:

A: 4 days (starts today, finishes in 4 days, due in 9 days)
B: 14 days (starts in 4 days, finishes in 18 days, due in 18 days)
C: 20 days (starts in 14 days, finishes in 20 days, due in 6 days)
D: 32 days (starts in 20 days, finishes in 32 days, due in 19 days)
E: 39 days (starts in 32 days, finishes in 39 days, due in 17 days)

Now we can calculate the average tardiness by (4+14+20+32+39)/5 = 21/2 = 10.5 days. However, this is not a listed answer choice. We need to round up to the nearest whole number, giving us an answer of 11 days, which matches choice (B). Therefore, (B) is the correct choice.

The Average Tardiness for the Jobs Listed in the Following