Correct Answer: 12 hours
Explanation:
A's 1 hour's work = | 1 | ; |
4 |
(B + C)'s 1 hour's work = | 1 | ; |
3 |
(A + C)'s 1 hour's work = | 1 | . |
2 |
(A + B + C)'s 1 hour's work = | ❨ | 1 | + | 1 | ❩ | = | 7 | . |
4 | 3 | 12 |
B's 1 hour's work = | ❨ | 7 | - | 1 | ❩ | = | 1 | . |
12 | 2 | 12 |
∴ B alone will take 12 hours to do the work.
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