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Two pipes X and Y can fill a cistern in 24 minutes and 32 minutes respectively. If both the pipes are opened together, then after how much time (in minutes) should Y be closed so that the tank is full in 18 minutes ?
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- 10
- 8
- 6
- 5
- 10
Correct Option: B
If pipe Y be closed after t minutes, then
According to question ,
| + | = 1 | ||
| 24 | 32 |
| ⇒ | = 1 - | = 1 - | = | ||||
| 32 | 24 | 4 | 4 |
| ⇒ t = | = 8 minutes | |
| 4 |
We can find required answer with the help of given formula :
Here , p = 24, q = 32, t = 18
| Required time = |  | q |  | 1 - |  |  | minutes | |
| p |
| Required time = | | 32 | | 1 - | | | minutes | |
| 24 |
| Required time = | | 32 | | 1 - | | | |
| 4 |
| Required time = 32 × | = 8 minutes | |
| 4 |
