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Math Expert V
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If p is a positive integer, is integer k prime?  [#permalink]

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If p is a positive integer, is integer k prime?

(1) 3p + 3 = k
(2) 7! + 3 = k

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Retired Moderator V
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Re: If p is a positive integer, is integer k prime?  [#permalink]

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Bunuel wrote:
If p is a positive integer, is integer k prime?

(1) 3p + 3 = k
(2) 7! + 3 = k

(1) \(k=3(p+1)\). Hence \(k\) is divisible by 3 and \(p+1 \implies k\) is not a prime. Sufficient.

(2) We have the specific value of \(k\), doesn't matter what value of \(k\) is. Sufficient.

In fact, \(k=7!+3\) is divisible by 3 so \(k\) is not a prime.

The answer is D.
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Re: If p is a positive integer, is integer k prime?  [#permalink]

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Bunuel wrote:
If p is a positive integer, is integer k prime?

(1) 3p + 3 = k
(2) 7! + 3 = k

FROM STATEMENT - I ( SUFFICIENT )

3p + 3 = k

Or, 3 ( p + 1 ) = k

So, k is divisible by 3 ; hence k can not be a prime number...

FROM STATEMENT - II ( SUFFICIENT )

7! + 3 = k

Or, 7*6*5*4*3*2*1 + 3 = k

Or, 3 ( 7*6*5*4*2*1 + 1 ) = k

So, k is divisible by 3 ; hence k can not be a prime number...

Thus, EACH statement ALONE is sufficient to answer the question asked, aswer will be (D)

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Re: If p is a positive integer, is integer k prime?  [#permalink]

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Hi all,
statement 1
If p=0, then k=3 -> so K prime! Am I missing something?
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Re: If p is a positive integer, is integer k prime?  [#permalink]

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hyppo0 wrote:
Hi all,
statement 1
If p=0, then k=3 -> so K prime! Am I missing something?

Hi

Its given that p is a positive integer, so we cannot take the case where p=0.
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Re: If p is a positive integer, is integer k prime?  [#permalink]

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I thought zero is both positive and negative.
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Re: If p is a positive integer, is integer k prime?  [#permalink]

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Bunuel wrote:
If p is a positive integer, is integer k prime?

(1) 3p + 3 = k
(2) 7! + 3 = k

#1 k= 3(P+1), so k can't be prime as it's definitely divided by 3.

#2 k= 3(1+x), where x>0 and Integer, so again k can't be prime as it's definitely divided by 3..

D Each statement independently sufficient. _________________
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ISB School Moderator G
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Re: If p is a positive integer, is integer k prime?  [#permalink]

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rashwiniyer wrote:
I thought zero is both positive and negative.

rashwiniyer

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GMAT 1: 650 Q44 V35 GMAT 2: 680 Q48 V34 Re: If p is a positive integer, is integer k prime?  [#permalink]

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Abhishek009 wrote:
Bunuel wrote:
If p is a positive integer, is integer k prime?

(1) 3p + 3 = k
(2) 7! + 3 = k

FROM STATEMENT - I ( SUFFICIENT )

3p + 3 = k

Or, 3 ( p + 1 ) = k

So, k is divisible by 3 ; hence k can not be a prime number...

FROM STATEMENT - II ( SUFFICIENT )

7! + 3 = k

Or, 7*6*5*4*3*2*1 + 3 = k

Or, 3 ( 7*6*5*4*2*1 + 1 ) = k

So, k is divisible by 3 ; hence k can not be a prime number...

Thus, EACH statement ALONE is sufficient to answer the question asked, aswer will be (D)

For statement 1, stating that if it is divisible by 3, then it is not prime I believe it is wrong: 3 is prime and is divisible by 3. The correct statement would be that for every value of x, the result won't be prime. Re: If p is a positive integer, is integer k prime?   [#permalink] 18 Jul 2019, 15:52
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