The average tardiness for the job listed in the table below under the longest processing time (LPT)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)16 days
B)14 days
C)15 days
D)13 days

Question

The average tardiness for the job listed in the table below under the longest processing time (LPT)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)16 days
B)14 days
C)15 days
D)13 days

Quizplus · Accepted Answer

Under LPT rule, we process jobs in decreasing order of processing time. 
Order of processing jobs: D → B → E → C → A
Tardiness of job A = max(0, 4 + 9 - 17) = 0
Tardiness of job B = max(0, 10 + 18 - 17) = 11
Tardiness of job C = max(0, 6 + 6 - 17) = 0
Tardiness of job D = max(0, 12 + 19 - 17) = 14
Tardiness of job E = max(0, 7 + 17 - 17) = 7
Average tardiness = (0 + 11 + 0 + 14 + 7)/5 = 32/5 = 6.4
Therefore, the average tardiness is 6.4 or approximately 15 days. The closest option is C.

The Average Tardiness for the Job Listed in the Table