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A tap can empty a tank in one hour. A second tap can empty it in 30 minutes. If both the taps operate simultaneously, how much time is needed to empty the tank?
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- 20 minutes
- 30 minutes
- 40 minutes
- 45 minutes
- 20 minutes
Correct Option: A
We know that , 1 hour = 60 minutes.
Rate of emptying the tank by the two taps are 1 /60 and 1 / 30 of the tank per minute respectively.
When both operate simultaneously ,
| Rate of emptying the tank = | + | = | = | = | of the tank per minute. | |||||
| 60 | 30 | 60 | 60 | 20 |
∴ Time taken by the two taps together to empty the tank = 20 minutes
Second method to solve this question :
Here, p = 60, q = 30
| Required time = |  |  | minutes | |
| (p + q) |
| Required time = | | | minutes | |
| 60 + 30 |
Required time = 20 minutes.
