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A and B can together finish a work in 30 days. They worked at it for 20 days and then B left. The remaining work was done by A alone in 20 more days.A alone can finish the work in
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- 60 days
- 54 days
- 48 days
- 50 days
Correct Option: A
(A + B) together do the work in 30 days.
| ∴ (A + B)’s 1 day’s work = | 30 |
∴ (A + B)’s 20 days’ work
| = | = | |||
| 30 | 3 |
| Remaining work = 1 – | = | |||
| 3 | 3 |
| ∵ Time taken by A in doing | work = 20 days | 3 |
∴ Time taken in doing 1 work
= 20 × 3 = 60 days.
Aliter : Using Rule 9,
Here, a = 30, b = 20, d = 20
A alone can finish the work in
| = | days | a - b |
| = | = 60 days | 30 - 20 |
