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A man and a boy can complete a work together in 24 days. If for the last six days man alone does the work then it is completed in 26 days. How long the boy will take to complete the work alone ?
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- 72 days
- 20 days
- 24 days
- 36 days
Correct Option: A
Suppose a man can complete the work in x days and that boys in y days.
According to question
| + | = 1 ......(i) × 13 | |||
| x | y |
| + | = 1 ......(ii) × 12 | |||
| x | y |
| + | = 13 | |||
| x | y |
| + | = 12 | |||
| x | y |
| ⇒ | = 1 ⇒ y = 72 days | y |
∴ Boys alone can complete the work in 72 days
Aliter : Using Rule 9,
Here, a = 24, b = 24 – 6 = 18 d = 26 days
Total time taken by B alone to complete the work
| = | - 6 | a - b |
( ∵ man has work d or 6 days)
| = | - 6 = 78 – 6 = 72 days | 24 - 18 |
