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Another Integer

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Another Integer

by heshamelaziry » Sun Nov 29, 2009 6:13 pm
Both X and Y are integers. In all cases where x is even, y is also even. Is xy even?

A- y - x is odd.

B- Sqrt of xy = 36


[spoiler]OA is D . The OE says that A is sufficient, even though the only way to satisfy A restriction is for Y to be even and x to be odd. How can the OE syas A is sufficient when the stem says that Both x and y must be positive ?????? There is no more explanation. [/spoiler]
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Source: — Data Sufficiency |
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by papgust » Sun Nov 29, 2009 9:59 pm
Look there are 2 cases for A (y - x = odd)

i. even - odd = odd
ii. odd - even = odd

Questions asks whether "Is xy even?"
i. even * odd = even (YES)
ii. odd * even = even (YES)

For both cases you get YES. So A is sufficient.
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by mehravikas » Mon Nov 30, 2009 4:41 pm
A is sufficient but your condition will not hold for this question. Because the question says that whenver x is even y is also even
therefore:

ii. odd(y) - even(x) = odd - is incorrect because when x is even it should be even(y) - even(x) = even

papgust wrote:Look there are 2 cases for A (y - x = odd)

ii. odd - even = odd
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by papgust » Mon Nov 30, 2009 9:08 pm
Yes you are right. Condition ii is not required for this problem. Didn't realize that. Thanks!
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