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Two pipes A and B can fill a tank in 36 hours and 45 hours respectively. If both the pipes are opened simultaneously, how much time will be taken to fill the tank?
Two pipes A and B can fill a tank in 36 hours and 45 hours respectively. If both the pipes are opened simultaneously, how much time will be taken to fill the tank?
1). 20 hours
2). 18 hours
3). 16 hours
4). 25 hours
1 answers
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Time taken by pipe A to fill a tank = 36 hours
⇒ Part of the tank filled by pipe A in 1 hour = 1/36 ----(1)
Time taken by pipe B to fill a tank = 45 hours
⇒ Part of the tank filled by pipe B in 1 hour = 1/45 ----(2)
Adding equations 1 and 2,
Part of the tank filled by pipe A and B both in 1 hour $(= \frac{1}{{36}} + \frac{1}{{45}} = \frac{{5 + 4}}{{180}} = \frac{9}{{180}} = \frac{1}{{20}})$
∴ Time taken by pipe A and B both to fill the tank completely = 20 hours