Indian Institute of Foreign Trade 2010 Solved Paper

Question : 15 of 135

Marks: +1, -0

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 normalrates 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 2hours, after which it supplied at its normal rate. In how much time, tank would be filled.

1.05 hours
2.05 hours
3.05 hours
None of the above

Validate

Solution:

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=21l

In 2 hrs, second pipe fills

(4.5+6)=10.5l

In 2 hrs, third pipe fills (16/3) l
In 2 hrs, tank filled

=(21+10.5+5.33)l=36.83l

Tank left to be filled

=(60-36.83)l=23.17l

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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