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# Is x an integer?

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Intern
Joined: 19 Sep 2005
Posts: 6

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08 Dec 2005, 06:33
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Is x an integer?

(1) $$\frac{x}{2}$$ is an integer
(2) 2x is an integer

OPEN DISCUSSION OF THIS QUESTION IS HERE: is-x-an-integer-127043.html
[Reveal] Spoiler: OA
Intern
Joined: 26 Sep 2005
Posts: 49
Re: Is x an integer? [#permalink]

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08 Dec 2005, 07:02

Your contention that x could be 1/2 means that x/2 would be 1/4 and this is not an integer while they say that x/2 is an integer.

Thus, if x/2 is an integer, x has to be an integer as well and thus we have A as the answer.
Intern
Joined: 19 Sep 2005
Posts: 6
Re: Is x an integer? [#permalink]

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08 Dec 2005, 07:08
You are right...it just clicked. Dumb mistake on my end. Dumb mistakes are my worse enemy!
Director
Joined: 10 Oct 2005
Posts: 718
Re: Is x an integer? [#permalink]

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08 Dec 2005, 07:14
manta_ray wrote:
Here is a DS question (Question 28 in the GMAT Review Official Guide 11th edition):

Is x an integer?

(1) x/2 is an integer

(2) 2x is an integer

My answer was E, neither is sufficient.

My rationale:
For (1) x could be 1/2 which would make x/2 an integer or x could be 4 which would make x/2 an integer

For (2) x could be 1/2 or 4 causing 2x to be an integer.

In both cases x could be an integer or a fraction. Therefore neither (1) nor (2) is sufficient for answering the question.

BUT in the answer guide the answer is A. Can someone please shed light on why the answer is A. The explaination is a poor one in the book I'm using.

Thanks!
CM

For x=1/2 x/2=1/4 I think Try to check with calculator
Senior Manager
Joined: 26 Jan 2008
Posts: 263
Re: Is x an integer? [#permalink]

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06 Feb 2008, 01:02
lmshaw wrote:
Hey guys, I am confused at this DS question...hope u can help clarify it for me.

#28 pg. 280
Is x an integer?
(1) x/2 is an integer
(2) 2x is an integer

So you can plug in 6 for x, and that will satisfy statement 1. But can't you also plug in 3/2 for x? The answer will be 3, which will still satisfy statement 1. So if x can both be an integer and non-integer, A can't be the answer right?

I don't know...it's past midnight here. Maybe I'm just getting delirious...??

plugging 3/2 in a will give 3/4 (since its x/2), which is not an integer. The answer should be (A)
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Joined: 15 Jan 2008
Posts: 31
Re: Is x an integer? [#permalink]

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06 Feb 2008, 01:09
oh god you're right! i am delirious. thanks!
CEO
Joined: 21 Jan 2007
Posts: 2739
Location: New York City
Re: Is x an integer? [#permalink]

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06 Feb 2008, 05:53
lmshaw wrote:
Hey guys, I am confused at this DS question...hope u can help clarify it for me.

#28 pg. 280
Is x an integer?
(1) x/2 is an integer
(2) 2x is an integer

So you can plug in 6 for x, and that will satisfy statement 1. But can't you also plug in 3/2 for x? The answer will be 3, which will still satisfy statement 1. So if x can both be an integer and non-integer, A can't be the answer right?

I don't know...it's past midnight here. Maybe I'm just getting delirious...??

we always want the minimum values for the numerator in divisibility questions. the min of x/2 is 2. all numerators will be multiples of 2 so x is an integer.
_________________

You tried your best and you failed miserably. The lesson is 'never try'. -Homer Simpson

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Joined: 09 Sep 2013
Posts: 15939
Re: Is x an integer? [#permalink]

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26 Mar 2015, 18:14
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).

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Posts: 39626
Re: Is x an integer? [#permalink]

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27 Mar 2015, 05:03
manta_ray wrote:
Is x an integer?

(1) $$\frac{x}{2}$$ is an integer
(2) 2x is an integer

Is x an integer?

(1) x/2 is an integer. For x/2 to be an integer x must be an integer --> $$\frac{x}{2}=integer$$ --> $$x=2*integer=integer$$, as you can see $$x$$ is not only an integer but an even integer. Sufficient.

(2) 2x is an integer --> x may or may not be an integer, for instance $$x=0.5$$ or $$x=1$$. Basically $$x$$ is of a type $$\frac{integer}{2}$$, hence $$x$$ may be an integer itself or half of an integer 0.5, 1.5, ... Not sufficient.

OPEN DISCUSSION OF THIS QUESTION IS HERE: is-x-an-integer-127043.html
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Re: Is x an integer?   [#permalink] 27 Mar 2015, 05:03
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