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A can complete a piece of work in 10 days, B in 15 days and C in 20 days. A and C worked together for two days and then A was replaced by B. In how many days, altogether, was the work completed ?
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- 12 days
- 10 days
- 6 days
- 8 days
Correct Option: D
Work done by (A + C) in 2 days
| = 2 |  | + |  | 10 | 20 |
| = 2 | | | = | = | 20 | 20 | 10 |
| Remaining work = 1 - | = | |||
| 10 | 10 |
(B + C)’s 1 day’s work
| = | + | = | = | |||||
| 15 | 20 | 60 | 60 |
∴ Time taken by (B + C) to finish
| part of the work | 10 |
| = | × | = 6 days | ||
| 7 | 10 |
∴ Total time = 2 + 6 = 8 days
