Question: 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 :
[A].8 days
10 days
12 days
15 days
[A].
[B].
[C].
[D].
Answer: Option C
Explanation:
| (A + B)’s 1 day’s work = | 1 | + | 1 | = | 1 | . | ||
| 15 | 10 | 6 |
| Work done by A and B in 2 days = | 1 | x 2 | = | 1 | . | ||
| 6 | 3 |
| Remaining work = | 1 – | 1 | = | 2 | . | ||
| 3 | 3 |
| Now, | 1 | work is done by A in 1 day. |
| 15 |
| 2 | work will be done by a in | 15 x | 2 | = 10 days. | |||
| 3 | 3 |
Hence, the total time taken = (10 + 2) = 12 days.