Question: A can do a piece of work in 4 hours; B and C together can do it in 3 hours, while A and C together can do it in 2 hours. How long will B alone take to do it?
[A].8 hours
10 hours
12 hours
24 hours
[A].
[B].
[C].
[D].
Answer: Option C
Explanation:
| A’s 1 hour’s work = | 1 | ; |
| 4 |
| (B + C)’s 1 hour’s work = | 1 | ; |
| 3 |
| (A + C)’s 1 hour’s work = | 1 | . |
| 2 |
| (A + B + C)’s 1 hour’s work = | 1 | + | 1 | = | 7 | . | ||
| 4 | 3 | 12 |
| B’s 1 hour’s work = | 7 | – | 1 | = | 1 | . | ||
| 12 | 2 | 12 |
B alone will take 12 hours to do the work.