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A is 50% as efficient as B. C does half of the work done by A and B together. If C alone does the work in 20 days, then A, B and C together can do the work in
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5 2 days 3 -
6 2 days 3 - 6 days
- 7 days
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Correct Option: B
If B alone completes the work in x days, A will do the same in 2x days
∴ (A + B)’s 1 day’s work
| + | = | = | ||||||
| x | 2x | 2x | 2x |
| and C’s 1 day’s work = | 4x |
| ∴ | = | |||
| 4x | 20 |
⇒ 4x = 3 × 20
| ⇒ x = | = 15 | 4 |
∴ (A + B + C)’s 1day’s work
| = | + | + | ||||
| 2x | x | 4x |
| = | + | + | ||||
| 30 | 15 | 20 |
| = | = | = | ||||
| 60 | 60 | 20 |
Hence, all three together will complete the work in
| or 6 | days | |||
| 3 | 3 |
