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Two pipes, P and Q can fill a cistern in 12 and 15 minutes respectively. Both are opened together, but at the end of 3 minutes, P is turned off. In how many more minutes will Q fill the cistern ?
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- 7 minutes
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7 1 minutes 2 - 8 minutes
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8 1 minutes 4
Correct Option: D
On the basis of given details in question ,
| Part of the tank filled in 3 minutes by pipes P and Q = 3 |  | + |  | ||
| 12 | 15 |
| Part of the tank filled in 3 minutes by pipes P and Q = 3 | | | = | = | |||
| 60 | 60 | 20 |
| So, Remaining part = 1 - | = | ||
| 20 | 20 |
| ∴ Time taken by Q = | × 15 = | = 8 | minutes. | |||
| 20 | 4 | 4 |
