Aptitude day 247

Problems on Pipes and cisterns:

1. A tank is filled by 3 pipes with uniform flow. The 1^st 2 pipes operating simultaneously fill the tank in the same time during which the tank is filled by the 3^rd pipe alone. The 2^nd pipe fills the tank 50 minutes faster than the 1^st pipe and 40 minutes slower than the 3^rd one. The time required by the 1^st pipe is:

Solution:

                  Let the time taken by pipe 1 be x.

                   1/x + 1/(x-50) = 1/(x-90)

                   By solving this, we get x = 150 minutes.

2. A tank is filled in 2 hours by 3 pipes A, B and C. The pipe C is thrice as fast as B and B is twice as fast as A. How much time will A alone take to fill the tank?

Solution:

                 Let the time taken by A be x.

                 1/x + 2/x + 6/x = 1/2.

                 x = 18 hours.