Three pipes A, B and C are connected to a tank. These pipes can fill the tank separately in 5 hours, 10 hours and 15 hours respectively. When all the three pipes were opened simultaneously, it was observed that pipes A and B were supplying water at 3/4th of their normal rates for the first hour after which they supplied water at the normal rate. Pipe C supplied water at 2/3rd of its normal rate for first 2 hours, after which it supplied at its normal rate. In how much time, tank would be filled.
Let the capacity of the tank be 60 litres.
Capacity of the first pipe = 12 l/hr
Capacity of the second pipe = 6 l/hr
Capacity of the third pipe = 4 l/hr
In 2 hrs, first pipe fills (9 + 12) l = 21 l
In 2 hrs, second pipe fills (4.5 + 6) = 10.5 l
In 2 hrs, third pipe fills (16/3) l
In 2 hrs, tank filled = (21 + 10.5 + 5.33) l = 36.83 l
Tank left to be filled = (60 - 36.83) l = 23.17 l
Time required = (23.17/22) hr = 1.05 hrs
Total time = 3.05 hrs
Hence, option C is the correct answer.
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