CMA Intermediate · Operations Management and Strategic Management · Scheduling and Queuing Models
Four jobs are processed on M1 then M2 (hours): A (5, 2), B (1, 6), C (9, 7), D (3, 8). What is the optimal sequence under Johnson's rule?
The optimal sequence is B-D-C-A. B has the smallest time (1 on M1) and goes first, A has the next smallest (2 on M2) and goes last, D (3 on M1) takes the next front slot, leaving C in the remaining position.
- AB-D-C-ACorrect
- BB-D-A-C
- CD-B-C-A
- DA-C-D-B
Explanation
Smallest time is 1 (B on M1), so B goes first. Next smallest is 2 (A on M2), so A goes last. Next is 3 (D on M1), so D goes second. C remains in third place. Sequence B-D-C-A. Putting A before C ignores that A's minimum is on M2.
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