Correct Option: C
According to question,
A and B can do a work in 12 days
| ∴ (A + B)’s one day’s work = | 1 | |
12 |
Similarly,
| (B + C)’s one day’s work = | 1 | |
15 |
| and (C + A)’s one day’s work = | 1 | |
20 |
On adding all three,
| ∴ 2 (A + B + C)’s one days’s work = | 1 | + | 1 | + | 1 |
12 | 15 | 20 |
| 2 (A + B + C)’s one days’s work = | 10 + 8 + 6 | = | 1 | |
120 | 5 |
| ⇒ (A + B + C)’s one days’s work = | 1 | |
10 |
∴ A, B and C together can finish the whole work in 10 days.
Second method to solve this question ,Here , x = 12 , y = 15 , z = 20
| Time taken = | 2xyz | |
xy + yz + zx |
| Time taken = | 2 × 12 × 15 × 20 | |
12 × 15 + 15 × 20 + 20 × 12 |
| Time taken = | 24 × 300 | |
180 + 300 + 240 |
| Time taken = | 7200 | = 10 days. |
720 |
