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A and B can complete a work in 15 days and 10 days respectively. They started doing the work together but after 2 days, B had to leave and A alone completed the remaining work. The whole work was completed in :
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- 10 days
- 8 days
- 12 days
- 15 days
Correct Option: C
Work done by (A + B) in 1 day
| = | + | = | = | |||||
| 15 | 10 | 30 | 6 |
| ∴ (A + B)’s 2 days’ work = | = | |||
| 6 | 3 |
| Remaining work = 1 - | = | |||
| 3 | 3 |
This part is done by A alone.
∵ one work is done by A in 15 days.
| ∴ | work is done in 15 × | = 10 days. | ||
| 3 | 3 |
∴ Total number of days
= 10 + 2 = 12 days
Aliter : Using Rule 20,
Here, m = 15, n = 10, p =2
A alone completed the work in
| = | days | n |
| = | 10 |
| = | = 10 days | 10 |
Total time taken= 10 + 2 = 12 days
