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If p is an integer greater than 1, is p a prime number?
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21 Dec 2015, 16:00
21 Dec 2015, 16:00
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If p is an integer greater than 1, is p a prime number?
(1) p is a factor of 13
(2) p is a factor of 78
(1) p is a factor of 13
(2) p is a factor of 78
Joined: 20 Mar 2014
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Concentration: Finance, Strategy
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GMAT 1: 750 Q49 V44 
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WE:Engineering (Aerospace and Defense)
Re: If p is an integer greater than 1, is p a prime number?
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21 Dec 2015, 18:56
21 Dec 2015, 18:56
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RSOHAL
If p is an integer greater than 1, is p a prime number?
(1) \(p\) is a factor of 13
(2) \(p\) is a factor of 78
(1) \(p\) is a factor of 13
(2) \(p\) is a factor of 78
The question asks whether p is a prime number.
Per statement 1, p is a factor of 13 and as such there are only 2 possible values of p = 1 or 13. But as it is given than p>1, p=13 is the only allowed value. Sufficient
Per statement 2, p is a factor of 78, thus p = 2 or 6 or 13 and you end up getting primes = 2 or 3 but also non primes = 6 or 78. Hence not sufficient.
A is the correct answer.
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Re: If p is an integer greater than 1, is p a prime number?
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02 May 2018, 09:00
02 May 2018, 09:00
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RSOHAL
If p is an integer greater than 1, is p a prime number?
(1) \(p\) is a factor of 13
(2) \(p\) is a factor of 78
(1) \(p\) is a factor of 13
(2) \(p\) is a factor of 78
Target question: Is p a prime number?
Given: p is an integer greater than 1
Statement 1: p is a factor of 13
The only positive factors of 13 are 1 and 13
Since we're told that p is greater than 1, we can conclude that p MUST equal 13
So, the answer to the target question is YES, p IS a prime number
Since we can answer the target question with certainty, statement 1 is SUFFICIENT
Statement 2: p is a factor of 78
The positive factors of 78 are 1, 2, 3, 6, 13, 26, 39 and 78
Since we're told that p is greater than 1, we can conclude that p COULD equal 2, 3, 6, 13, 26, 39 or 78
If p = 2, then the answer to the target question is YES, p IS a prime number
If p = 6, then the answer to the target question is NO, p is NOT a prime number
Since we cannot answer the target question with certainty, statement 2 is NOT SUFFICIENT
Answer: A
Cheers,
Brent
