Manhattan Ds

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Manhattan Ds

by venmic » Sun Jan 15, 2012 11:18 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.

A
Source: — Data Sufficiency |

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by Anurag@Gurome » Sun Jan 15, 2012 11:31 pm
venmic wrote: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.

A
It is given that pool X has 2/7th 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. This means pool Y has 6/7 - 2/7 = 4/7 of water.
For Pool X and Pool Y are to have equal volumes of water, if we move 1/7 water from pool Y to pool X, then both the pools will have 3/7 of water; SUFFICIENT.

(2) Pool X has a capacity of 14,000 gallons but there is info on pool Y; NOT sufficient.

The correct answer is A.
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by GMATGuruNY » Mon Jan 16, 2012 8:32 am
venmic wrote: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.

A
Statement 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.
Let the capacity of Pool X = 14 units.
Amount in Pool X = (2/7)*14 = 4 units.
After the transfer from Pool Y, the amount in Pool X = (6/7)*14 = 12 units. This is the total amount of water.
The amount transferred from Pool Y = 12-4 = 8 units.
In order for each pool to have the same amount -- 6 units -- 2 of the 8 units in Pool Y must be transferred to Pool X:
2/8 = 1/4 = 25%.

If we multiply the capacity of Pool X by a factor, all of the subsequent values will be multiplied by the SAME FACTOR, so the resulting percentage of Pool Y that must be transferred WILL REMAIN 25%.
SUFFICIENT.

Statement 2: Pool X has a capacity of 14,000 gallons.
No information about Pool Y.
INSUFFICIENT.

The correct answer is A.
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