Question:
Three pipes A, B and C can fill a tank in 6 hours. After working at it together for 2 hours, C is closed and A and B can fill the remaining part in 7 hours. The number of hours taken by C alone to fill the tank is:
[A].10
12
14
16
Three pipes A, B and C can fill a tank in 6 hours. After working at it together for 2 hours, C is closed and A and B can fill the remaining part in 7 hours. The number of hours taken by C alone to fill the tank is:
[A].
[B].
[C].
[D].
Answer: Option C
Explanation:
| Part filled in 2 hours = | 2 | = | 1 |
| 6 | 3 |
| Remaining part = | 1 – | 1 | = | 2 | . | ||
| 3 | 3 |
| (A + B)’s 7 hour’s work = | 2 |
| 3 |
| (A + B)’s 1 hour’s work = | 2 |
| 21 |
C’s 1 hour’s work = { (A + B + C)’s 1 hour’s work } – { (A + B)’s 1 hour’s work }
| = | 1 | – | 2 | = | 1 | ||
| 6 | 21 | 14 |
C alone can fill the tank in 14 hours.