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Filling the pool

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Filling the pool

by cornell2005 » Mon Aug 11, 2008 5:45 pm
If Pool Y currently contains more water than Pool X, and if Pool X is currently filled to 2/7 of its capacity, what percent of the water currently in Pool Y needs to be transferred to Pool X if Pool X and Pool Y are to have equal volumes of water?

(1) If all the water currently in Pool Y were transferred to Pool X, Pool X would be filled to 6/7 of its capacity.

(2) Pool X has a capacity of 14,000 gallons.

Thanks in advance.
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Source: — Data Sufficiency |
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by floravaze » Tue Aug 12, 2008 2:28 am
is the answe A?
let me explain why i think so.Firstly,i am assumimg that the two pools have equal capacity.
A s sufficient because we can deduce using the stem that what is added to pool A is 4/7 q'ty of water(6/7 -2/7) which is the quantity in pool Y and you can proceed from there.
B is not sufficient because it tells us nothing about what is found in Y.We only deduce that pool x needs 10000 more gallons of water.
so answer is A.
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by pepeprepa » Tue Aug 12, 2008 2:59 am
I don't think you need to assume the two pools have equal capacity.
We have
current amount in Y > 2/7X
"If all the water currently in Pool Y were transferred to Pool X, Pool X would be filled to 6/7 of its capacity."
Thanks to this sentence we can infer that the current amount in Y is 4/7X:
4/7X>2/7X
1/7 (+/- 14%) from pool Y has to be transferred to pool X

Agree with A
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by cornell2005 » Tue Aug 12, 2008 4:16 am
I would have chosen A as well. But I'm having trouble solving the last step. (you dont need to for DS, but I feel like I should be able to)

can you please explain how you get from 4/7x > 2/7x saying that 1/7 of Y must be added to X? Thanks.
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by pepeprepa » Tue Aug 12, 2008 4:31 am
let's say X=1 (total possible capacity)
By one side you have Y with 4/7 and X with 2/7
you take 1/7 from Y and you put it to X
Therefore, you have 3/7 for each
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by cornell2005 » Tue Aug 12, 2008 11:02 am
ahh i see.. thanks. I got caught up on the fact that you dont know Y's capacity.
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by kshin78 » Tue Aug 12, 2008 2:21 pm
pepeprepa wrote:I don't think you need to assume the two pools have equal capacity.
We have
current amount in Y > 2/7X
"If all the water currently in Pool Y were transferred to Pool X, Pool X would be filled to 6/7 of its capacity."
Thanks to this sentence we can infer that the current amount in Y is 4/7X:
4/7X>2/7X
1/7 (+/- 14%) from pool Y has to be transferred to pool X

Agree with A
quick question. shouldn't the % be 1/7 of 4/7 which is same as 1/4, therefore 25% of the capacity? i agree w/ the answer but wanted to solve the prob...
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