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Two pipes A and B can fill a tank with water in 30 minutes and 45 minutes respectively. The water pipe C can empty the tank in 36 minutes. First A and B are opened. After 12 minutes C is opened. Total time (in minutes) in which the tank will be filled up is :
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- 30
- 12
- 36
- 24
- 30
Correct Option: D
As per the given in question , we have
| Part of tank filled by pipes A and B in 1 minute = | + | = | = | part | ||||
| 30 | 45 | 90 | 18 |
| ∴ Part of tank filled in 12 minutes = | = | part | ||
| 18 | 3 |
| Remaining part = 1 – | = | part | ||
| 3 | 3 |
When pipe C is opened,
| Part of tank filled by all three pipes = | + | - | |||
| 30 | 45 | 36 |
| Part of tank filled by all three pipes = | = | = | |||
| 180 | 180 | 36 |
| ∴ Time taken in filling 1/3 part = | × 36 = 12 minutes | |
| 3 |
∴ Total time = 12 + 12 = 24 miuntes
