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Pipes P and Q can fill a tank in 10 and 12 hours respectively and C can empty it in 6 hours. If all the three are opened at 7 a.m., at what time will one-fourth of the tank be filled ?
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- 10 a.m.
- 10 p.m.
- 11 p.m.
- 11 a.m.
- 10 a.m.
Correct Option: B
From the given question ,
When all three pipes are opened , then
| Part of tank filled in 1 hour = | + | - | |||
| 10 | 12 | 6 |
| Part of tank filled in 1 hour = | = | ||
| 60 | 60 |
∴ The tank will be filled in 60 hours.
| ∴ One fourth of the tank will be filled in 15 hours = |  | × 60 |  | i.e the tank will be filled at 10 p.m. | |
| 4 |
