Question

7. Five jobs must be scheduled. Each of the jobs must be processed on two machines (A and B) in the same order. The processing times are listed below. In what order should the jobs be processed? A 16 10 Job 1 2 3 4 5 B 2 10 4 3 2 20 12 1 A. 1-2-3-4-5 B. 3-5-2-4-1 C. 4-5-3-2-1 D. 4-1-2-3-5 E. 5-4-3-2-1

Answer 1

Answer: E. 5-4-3-2-1

Explanation:

As per Johnson's rule, the job with shortest processing time (SPT) need to be scheduled first. If SPT is for Machine 1(A) then it should be scheduled as early as possible. If SPT is for Machine 2 (B) then it should be scheduled as late as possible.

Job 5 - Processing time 1 for Machine A so it should be scheduled first - Sequence Order 1

Job 1 - Processing time 2 for Machine B so it should be scheduled last - Sequence Order 5

Job 4 - Processing time 2 for Machine B so it should be scheduled Second - Sequence Order 2

Job 3 - Processing time 3 for Machine A so it should be scheduled third - Sequence Order 3

Job 2 is the last job to be scheduled - Sequence Order 4

Sequence Order: 5 - 4 - 3 - 2 - 1