SOLUTION: Two pipes can be used to fill a water tank. If used alone the first pipe could fill the tank in 27 minutes; the second pipe could fill it in 54 minutes. A third pipe, which is conn

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: Two pipes can be used to fill a water tank. If used alone the first pipe could fill the tank in 27 minutes; the second pipe could fill it in 54 minutes. A third pipe, which is conn      Log On


   

Question 692396: Two pipes can be used to fill a water tank. If used alone the first pipe could fill the tank in 27 minutes; the second pipe could fill it in 54 minutes. A third pipe, which is connected to an outlet of the tank, can empty the tank in 36 minutes. If all pipes are opened when the tank is empty, how long will it take the tank to be filled?
Answer by partha_ban(41) About Me  (Show Source):
You can put this solution on YOUR website!
1st pipe alone can fill the tank in 27 mins.
So in 1 minute, it can fill 1/27 part of the tank.
2nd pipe alone can fill the tank in 54 mins.
So in 1 minute, it can fill 1/54 part of the tank.
3rd pipe can empty the tank in 36 mins.
So in 1 minute, it can empty 1/36 part of the tank.
When all pipes are open, in 1 minute tank fills
1%2F27+%2B+1%2F54+-+1%2F36
= 1%2F36 parts (do the calculation yourself)
So, they will fill the tank in 1 / (1/36) mins = 36 mins.