Five jobs are to be scheduled in two machines in a manufacturing shop. All the five jobs undergo…
Johnson's rule picks the smallest remaining processing time: if it is on Machine 1 the job is placed as early as possible, if on Machine 2 as late as possible. Job 3 (2 on…
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Five jobs are to be scheduled in two machines in a manufacturing shop. All the five jobs undergo processing in both machines as per table.
| Processing Time: Machine 1 | Machine 2 | ||
|---|---|---|---|
| A. | Job 1 | 4 | 7 |
| B. | Job 2 | 6 | 3 |
| C. | Job 3 | 2 | 3 |
| D. | Job 4 | 7 | 7 |
| E. | Job 5 | 8 | 6 |
Identify the best sequence using Johnson's rule.
Answer and explanation
Correct answer C
Johnson's rule picks the smallest remaining processing time: if it is on Machine 1 the job is placed as early as possible, if on Machine 2 as late as possible. Job 3 (2 on M1) goes first, Job 2 (3 on M2) goes last, Job 1 (4 on M1) goes second, Job 5 (6 on M2) goes fourth, and Job 4 fills the middle, giving Job 3, Job 1, Job 4, Job 5, Job 2, i.e. C, A, D, E, B.
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