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Question
Six jobs are performed on Machines M1 and M2 respectively. Time in hours taken by each job on each machine is given below:
| Jobs `→` | A | B | C | D | E | F |
| Machines `↓` | ||||||
| M1 | 3 | 12 | 5 | 2 | 9 | 11 |
| M2 | 8 | 10 | 9 | 6 | 3 | 1 |
Determine the optimal sequence of jobs and find total elapsed time. Also find the idle time for machines M1 and M2.
Solution:
Given jobs can be arranged in optimal sequence as,
| D | A | C | B | E | F |
| Jobs | Machine M1 | Machine M2 | ||
| In | Out | In | Out | |
| D | 0 | 2 | `square` | 8 |
| A | 2 | 5 | 8 | 16 |
| C | 5 | 10 | 16 | 25 |
| B | 10 | 22 | 25 | 35 |
| E | 22 | 31 | 35 | 38 |
| F | 31 | 42 | `square` | 43 |
Total Elapsed time = `square` hrs.
Idle time for Machine M1 = 43 – 42 = 1 hour.
Idle time for Machine M2 = `square` hrs.
Solution
Given jobs can be arranged in optimal sequence as,
| D | A | C | B | E | F |
| Jobs | Machine M1 | Machine M2 | ||
| In | Out | In | Out | |
| D | 0 | 2 | 2 | 8 |
| A | 2 | 5 | 8 | 16 |
| C | 5 | 10 | 16 | 25 |
| B | 10 | 22 | 25 | 35 |
| E | 22 | 31 | 35 | 38 |
| F | 31 | 42 | 42 | 43 |
Total Elapsed time = 43 hrs.
Idle time for Machine M1 = 43 – 42 = 1 hour.
Idle time for Machine M2 = 6 hrs.
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