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by resilient » Wed Feb 06, 2008 6:02 pm
Is n and integer?

1. n^2 is an integer
2. ROot N is an integer

I chose D but QA is B

why isnt a sufficient also. I plugged in numbers by the way
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by simplyjat » Wed Feb 06, 2008 8:59 pm
Plugging numbers is not always the best approach. I just read an excellent post

Square of every integer will always be an integer, but square root of every number will not be an integer...
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by Stuart@KaplanGMAT » Wed Feb 06, 2008 9:27 pm
When you pick numbers, your goal is to get both a yes and a no answer to the question - if you can get both, a statement is insufficient.

(1) n^2 is an integer.

If we pick n=3 (we're allowed to, since 3^2 = 9 which is an integer), we get a "yes" answer to the question "is n an integer".

However, if we pick n = root3 (we're allowed to, since (root3)^2 = 3 which is an integer), we get a "no" answer to the question "is n an integer".

Since we can get both a yes and a no answer, statement (1) is insufficient.
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