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Question
In a factory there are six jobs to be performed each of which should go through two machines A and B in the order A - B. The processing timing (in hours) for the jobs arc given here. You are required to determine the sequence for performing the jobs that would minimize the total elapsed time T. What is the value of T? Also find the idle time for machines · A and B.
| Jobs | J1 | J2 | J3 | J4 | J5 | J6 |
| Machine A | 1 | 3 | 8 | 5 | 6 | 3 |
| MAchine B | 5 | 6 | 3 | 2 | 2 | 10 |
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Solution
The order is A to B, hence the required sequence is
| J1 | J2 | J6 | J3 | J5 | J4 |
or
| J1 | J6 | J2 | J3 | J4 | J5 |
| Job Sequence |
Machine A | Machine B | ||
| Time in |
Time out |
Time in |
Time out |
|
| J1 | 0 | 1 | 1 | 6 |
| J2 | 1 | 4 | 6 | 12 |
| J6 | 4 | 7 | 12 | 22 |
| J3 | 7 | 15 | 22 | 25 |
| J5 | 15 | 21 | 25 | 27 |
| J4 | 21 | 26 | 27 | 29 |
Total elapsed time T = 29 hours
Idle time for A = 3 hours
Idle time for B = 1 hour.
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