A cistern has two pipes, one can fill it with water in 8 hours, other can empty it in 5 hours. In how many hours will the cistern be empties if both the pipes are opened together when three fourth of the cistern is already full of water?
[SSC CGL 2005]
Answer: Option B
Now as one pipe fills the cistern and other empties it,
According to the formula, if pipe A can comletely fill a tank in x hours and pipe B can empty the same tank in y hours, then the time taken to fill the tank when both the pipes are opened simultaneously is hours.
Two pipes A and B can fill a water tank in 12 min and 24 min respectively. Third pipe C can empty at the tank at the rate of 3 gallons per minute. If A, B and C opened together fill the tank in 15 minutes, the capacity of the tank in gallons is___
[SSC CPO 2007]
Answer: Option C
Time taken by all tohethet to fill the tank is 15 minutes
Let the capacity of the tank be x gallons
Quantity of water filled in the tank in 1 min when all the pipes A, B and C are opened simultaneously,