Table J.7
The following four jobs just arrived (end of hour 0) at Workstation A. They are the only ones waiting to be processed.

-Using the information in Table J.7 and the S/RO rule, what is the average flow time at Workstation A?
A) fewer than or equal to 14.0 hours
B) greater than 14.0 but fewer than or equal to 14.5 hours
C) greater than 14.5 but fewer than or equal to 15.0 hours
D) greater than 15.0 hours

Question

Table J.7
The following four jobs just arrived (end of hour 0) at Workstation A. They are the only ones waiting to be processed.
 
-Using the information in Table J.7 and the S/RO rule, what is the average flow time at Workstation A?
A) fewer than or equal to 14.0 hours 
B) greater than 14.0 but fewer than or equal to 14.5 hours 
C) greater than 14.5 but fewer than or equal to 15.0 hours 
D) greater than 15.0 hours

Quizplus · Accepted Answer

Using the S/RO rule, the jobs will be processed in the following order: 
1. TB1252_00
2. TB1252_00
3. TB1252_00
4. TB1252_00
The processing time for each job is:
TB1252_00: 8 hours
TB1252_00: 8 hours
TB1252_00: 10 hours
TB1252_00: 12 hours
Therefore, the average flow time for these four jobs is (8+16+26+38)/4 = 22 hours. Since the answer choices suggest ranges, the closest range is C, which is greater than 14.5 but fewer than or equal to 15.0 hours.

Table J.7 The Following Four Jobs Just Arrived (End of Hour 0)