CAT 2018 Question Paper Shift 1 Solved Paper

Let the rate of each filling pipes be 'x 1‌ts‌/‌hr ' similarly, the rate of each draining pipes be 'y lts‌/‌hr '.
As per the first condition,
Capacity of tank =(6x−5y)×6..........(i)
Similarly, from the second condition,
Capacity of tank =(5x−6y)×60...... (ii)
On equating (i) and (ii), we get
(6x−5y)×6=(5x−6y)×60
or, 6x−5y=50x−60y
or, 44x=55y
or, 4x=5y
or,x=1.25y
Therefore, the capacity of the tank lts
Effective rate of 2 filling pipes and 1 draining pipe =(2x−y)=(2.5y−y)=1.5y
Hence, the required time =15y/1.5y=10 hours.