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If n=p/q ( p and q are nonzero integers), is n an integer?
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28 Oct 2009, 03:17
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If n=p/q ( p and q are nonzero integers), is n an integer? (1) n^2 is an integer (2) (2n+4)/2 is an integer == Message from the GMAT Club Team == THERE IS LIKELY A BETTER DISCUSSION OF THIS EXACT QUESTION. This discussion does not meet community quality standards. It has been retired. If you would like to discuss this question please repost it in the respective forum. Thank you! To review the GMAT Club's Forums Posting Guidelines, please follow these links: Quantitative  Verbal Please note  we may remove posts that do not follow our posting guidelines. Thank you.
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Re: Is n an integer
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28 Oct 2009, 03:39
divyakatas wrote: IMO D will appreciate the explanation
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Re: Is n an integer
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28 Oct 2009, 08:01
I think it is D...Here is the explanation.... If n=p/q ( p and q are nonzero integers), is n an integer?
(1) n^2 is an integer Condition says n2 is integer....means n2 has to be a positive square number (square cannot be negative).... 4, 9, 16.... Why only perfect square because if n is not an integer than n2 cannot be an integer too (but condition 1 says n2 is an integer)... so Sufficient... (2) (2n+4)/2 is an integer As per condition 2....(2n+4)/2 is an integer.... it can only be integer ..if n is an integer e.g. 10, 5, 0, 4, 9, 50 etc.... means n has to be integer for this ....(2n+4)/2 is an integer...... so Sufficient...
please correct if my understanding is wrong....



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Re: Is n an integer
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28 Oct 2009, 10:31
Hussain15 wrote: If n=p/q ( p and q are nonzero integers), is n an integer?
(1) n^2 is an integer (2) (2n+4)/2 is an integer Yes the answer is D, but there is a catch in statement 1 that has been ignored so far. So for the sake of clarification: The fact that n^2 is an integer need not imply that n is an integer. If n=sqrt(3) then n^2 = 3 which is an integer. BUT remember we are told in the Q that n=p/q, where p and q are nonzero integers. Since we cannot get a squareroot of a number which is not a perfect square by dividing to integers the statement IS sufficient. Statement 2 is obviously sufficient  If in doubt just plug in numbers.



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Re: Is n an integer
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28 Oct 2009, 10:54
D
(A) n=sqrt(x) is integer and given n=p/q [e.g sqrt(2) is irrational, but out of scope due to given info] sufficient (B) (2n+4)/2 = n+2. sufficient



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Re: Is n an integer
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28 Oct 2009, 17:01
IMO D, andershv I like your explanation
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Re: Is n an integer
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28 Oct 2009, 19:59
Thanks for the input! Obviously the trick was in point 1. Answer is "D". Can we use the concept of prime factorization to determine the sufficiency of statement 1?? I mean some technical way, rather plugging in the numbers.
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Re: Is n an integer
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30 Oct 2009, 18:31
I think, this problem is better solved by not plugging numbers, but by knowing the number properties.
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Re: If n=p/q ( p and q are nonzero integers), is n an integer?
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15 Aug 2017, 04:48
Hello from the GMAT Club BumpBot! Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up  doing my job. I think you may find it valuable (esp those replies with Kudos). Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email. == Message from the GMAT Club Team == THERE IS LIKELY A BETTER DISCUSSION OF THIS EXACT QUESTION. This discussion does not meet community quality standards. It has been retired. If you would like to discuss this question please repost it in the respective forum. Thank you! To review the GMAT Club's Forums Posting Guidelines, please follow these links: Quantitative  Verbal Please note  we may remove posts that do not follow our posting guidelines. Thank you.
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Re: If n=p/q ( p and q are nonzero integers), is n an integer?
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