SOLUTION: Please help me solve this question: Pipe A can fill a tank in 5 h. Pipe B can fill it in 2 h less time than it takes Pipe C, a drainpipe, to empty the tank. With all three pipes op

Question 934291: Please help me solve this question: Pipe A can fill a tank in 5 h. Pipe B can fill it in 2 h less time than it takes Pipe C, a drainpipe, to empty the tank. With all three pipes open, it takes 3 h to fill the tank. How long would it take to pipe C to empty it?
Found 2 solutions by josgarithmetic, josmiceli:
Answer by josgarithmetic(39617) (Show Source): You can put this solution on YOUR website!
Understand that the signs for the rate for pipe B and pipe C are opposite, and you want to give a variable to the time for pipe C to empty the tank.

RATES are as TANK per HOURS
Pipe A,
Pipe B,
Pipe C,
All pipes open at the same time, tanks per hour.

The rate for all pipes open at the same time is the sum of their individual rates.
... You see what to do?
Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
Pipe A's rate of filling is:
( 1 tank filled ) / ( 5 hrs )
------------------------
Let = pipe C's time to
empty the tank, so C's rate
of emptying is:
( minus 1 tank filled ) / ( t hrs )
-----------------------------
Pipe B's rate of filling is:
( 1 tank filled ) / ( t - 2 hrs )
-------------------------
With all 3 pipes open, the rate of filling is:
( 1 tank filled ) / ( 3 hrs ), so I can say:

Multiply both sides by:

( can't use negative time )
Pipe C can empty the tank in 5 hrs
check:

OK

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