kzivrev wrote:
I think that this question contains some small portion of ambiguity. Im saying this because is not very clear what the author ment( maybe because im not native english), does the water goes from the 500G tank to the 200G tank, or they independetly work on their own. That is why PareshGmat and I was also in the same basket assuming that teh tanks are conected and need to equalize and tehre is a limited 700G and of course need to have 350G each, and got stuck. Of course if they are not concetd than the equation is streight forward.
Does someone else had the same issue?
It doesn't matter whether the water goes from one tank to another or whether it is pumped out and in independently. Note that you are clearly given that "water is being pumped out of tank X at a
rate of K gallons per minute and water is being added to tank Y at a
rate of M gallons per minute". The pumping out and pumping in take place at different rates. Now whether the water is pumped out of the big tank at a certain rate, stored and then pumped in the smaller tank at another rate or whether they have independent water sources - it doesn't matter. We want the water in the two tanks to be equal.
Say two people A and B are standing 300 steps away and they start walking toward each other. When will they meet? It their speeds are equal, then they will meet in the center i.e. 150 steps away from each end (that would be the case if K = M). But if their speeds are different, they could meet anywhere else. So if speed of A is twice the speed of B, A will cover 200 steps while B will cover 100 steps and they will meet 200 steps away from A's original position.
Similarly if K is twice of M, in the time that the big tank loses 200 gallons, the small tank will gain 100 gallons - they will both have 300 gallons of water each.
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Karishma
Veritas Prep GMAT Instructor
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