Random Sequence:

The following flow time has been found with the random based job sequencing rule

Table: Flow Time of Random Sequencing

From the above analysis, total flow time may be easily calculated. Total flow time

= 245 + 465 + 1245 + 1420 = 3375 min.        

Therefore, average flow time = 3375/4 = 843.75 min.

Now, compare the due date of the job with its flow time. From the comparison it has been found that Job (J4) and Job (J1) shall be on time, whereas, Job (J2) and Job (J3) shall become late by some amount of time.

Therefore, average lateness of the jobs = (0 + 0 +465 + 1030)/4 = 373.75 min. The results attained from the above analysis are given in Table:

Table: Comparison of Different Job-sequencing Rule

From the above table, SPT has illustrated better performance than other job sequencing rules. SPT based sequence shall always perform better than other and similar can be proved mathematically.