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# Is X a prime integer?

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Is X a prime integer? [#permalink]  01 Apr 2010, 06:16
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Is X a prime integer?

(1) x! is not divisible by 5
(2) |x|! is divisible by 6

Sorry to open a new thread:
gmat-diagnostic-test-question-79332.html

Doesnt 3 and 4 both satisfy condition 1 and 2. So ideally we dont have any firm answer.
3! and 4! are not divisible by 5 and are divisible by 6

[Reveal] Spoiler: OA

Last edited by Bunuel on 05 Jul 2013, 00:24, edited 1 time in total.
Edited the question and added the OA.
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Re: Is X a prime integer? [#permalink]  01 Apr 2010, 06:59
rohitgoel15 wrote:
Sorry to open a new thread:
gmat-diagnostic-test-question-79332.html

Is X a prime integer?

(1) x! is not divisible by 5
(2) |x|! is divisible by 6
Doesnt 3 and 4 both satisfy condition 1 and 2. So ideally we dont have any firm answer.
3! and 4! are not divisible by 5 and are divisible by 6

st 1) x can be 1,2,3,4. Not sufficient
st 2) |x| > 2 . Not sufficient

combinging, we get x = 3 or 4 .. not sufficient

E
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Re: Is X a prime integer? [#permalink]  02 Apr 2010, 16:05
I think it is A.because when x! isn't divisible by 5 so it must be 4! or 3! when it says that x is a prime number so it should be 3! so A is the answer.
Am I wrong?
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Re: Is X a prime integer? [#permalink]  02 Apr 2010, 16:11
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Re: Is X a prime integer? [#permalink]  02 Apr 2010, 18:35
Statement 1 X<5 NS
Statement 2 X<=3 NS

Combined 3,4 satisfy it and 3 is a prime and 4 is not so NS
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Re: Is X a prime integer? [#permalink]  03 Apr 2010, 00:28
I am also getting "E" as the answer.

In OE, the statement 2 is summaized as x <= -3 or x >= 3.

I couldnt understand this. Why 4 is not considered?
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Re: Is X a prime integer? [#permalink]  21 Jun 2010, 20:38
Is X a prime integer?

(1) x! is not divisible by 5
(2) |x|! is divisible by 6

Is factorial always an integer? can we have a non-integer factorial? Can factorial be negative? Someone please clarify....
if factorial is always an integer and positive, then
1. x=0,1,2,3,4
2. X=3,4,....

1+2
x=3,4 E
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Re: Is X a prime integer? [#permalink]  22 Jun 2010, 03:11
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Yes, OA for this one is not correct.

Is $$x$$ a prime integer?

(1) $$x!$$ is not divisible by 5 --> $$x=0$$, $$1$$, $$2$$, $$3$$, or $$4$$. Not sufficient.

(2) $$|x|!$$ is divisible by 6 --> $$|x|>2$$. Not sufficient.

(1)+(2) $$x=3$$ (prime) or $$x=4$$ (not prime). Not sufficient.

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Re: Is X a prime integer? [#permalink]  22 Jun 2010, 07:10
Thanks Bunuel for the detailed explanation
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Re: Is X a prime integer? [#permalink]  16 Dec 2013, 07:19
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Re: Is X a prime integer? [#permalink]  25 Jun 2015, 07:18
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Re: Is X a prime integer? [#permalink]  08 Sep 2015, 04:50
There is one piece that is missing from previous explanations:

Statement 2 suggests that X can be positive or negative because absolute value of |X|. Because X be either negative or positive (and we can't figure out which), that means that we cannot determine whether it is prime. For example, 3 is prime, -3 is not.
Re: Is X a prime integer?   [#permalink] 08 Sep 2015, 04:50
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