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OG - DS - #146

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cindyqtran
 Post subject: OG - DS - #146
 Post Posted: Sat Jun 23, 2007 10:43 pm 
Page 336 from the 11th edition OFFICIAL GUIDE Question 146

can you please explain why n^2 is an integer is NOT sufficient? if N^2 is an integer, it means that N is NOT a fraction, therefore an integer, correct?

Thanks.
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StaceyKoprince
 Post subject:
 Post Posted: Mon Jun 25, 2007 7:33 pm 
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ManhattanGMAT Staff


Posts: 6077
Location: San Francisco
Please don't forget to post the entire text of the question and answer choices. Others would like to study from the questions you ask, and that is made much more difficult if they cannot see the whole question. Unfortunately, there are too many requests every day for the instructors to look up and transcribe all of the questions.

Thanks!

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Stacey Koprince
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sharad
 Post subject: OG - DS # 146
 Post Posted: Wed Sep 12, 2007 7:30 pm 
Have trouble understanding the solution to the same question... so here's the problem:

#146
Is n an integer?
1) n^2 is an int
2) sqrt n is an int

OG Ans: B

Why isn't it D?
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sharad
 Post subject: OG - DS # 146
 Post Posted: Wed Sep 12, 2007 7:34 pm 
Found this post - that explains why... makes sense... thanks,

DS question

is n an integer?
1) n^2 is an integer

in the statement above, can anyone provide me with an example of n not being an integer when n^2 is an integer? thanks.

If n = 1.414.....(the square root of 2), then n is not an integer when n^2 is. As Saurabh mentioned, this works with any non-perfect square situation, such as root3, root5, root6, root7, etc. Notice that with a perfect square, such as the number 4, this does not hold true.

Hope this helps!
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