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Question
Solve the following minimal assignment problem and hence find minimum time where '- ' indicates that job cannot be assigned to the machine :
| Machines | Processing time in hours | ||||
| A | B | C | D | E | |
| M1 | 9 | 11 | 15 | 10 | 11 |
| M2 | 12 | 9 | - | 10 | 9 |
| M3 | - | 11 | 14 | 11 | 7 |
| M4 | 14 | 8 | 12 | 7 | 8 |
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Solution
Step 1 : The problem is unbalanced. So, it is balanced by introducing a dummy machine M5 with O.
Step 2 : Minimum element of each row is subtracted from every element in that row.
Step 3 : Zero element are covered with minimum number of straight lines :
Minimum number of lines = order of matrix = 5
∴ Optimum solution is reached
Step 4 : Making assignment at single zero of the row and then at single zero of the column.
The optional assignment is
M1 → A
M2 → B
M3 → E
M4 → D
M5 → C
∴ Minimum Time= 9 + 9 + 7 + 7 + 0 = 32 hrs.
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| B | 11 | 0 | 10 | 0 |
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C →IV D →`square`
Total minimum time = `square` hours.
