Problema Solution
A tank is filled by two pipes. One can fill the tank in 15 hours, while the other can fill the tank in 10 hours. Together, these pipes can fill the tank in 6 hours. A third pipe, which is said to be able to fill the tank in 6 hours, is installed. If this is true, then how long should it take all three pipes to fill the one tank?
Answer provided by our tutors
One can fill the tank in 15 hours.
In one hour, it can fill - 1/15th of the tank.
Another one can fill the tank in 10 hours.
In one hour, it can fill - 1/10th of the tank.
A third one can fill the tank in 6 hours.
In one hour, it can fill - 1/6 th of the tank.
So part of the tank filled in one hour due to all three pipes working together is
1/10 + 1/15 + 1/6 = 2/30 + 3/30 + 5/30 = 10/30 = 1/3
Together they can fill 1/3rd of the tank in 1 hour
So, time taken to fill the whole tank will be 1/(1/3) = 3 hours [ANS]