Is integer N a prime number ?

[goelmohit2002]

Is integer N a prime number ?
1) All the prime factors of N are greater than root N.
2) All the prime factors of N are greater than N/2.

OA = A. Can someone please tell how...IMO it should be D

[lrlorenzon]

I believe that 2) is insufficient because you can take N<0. [editor: the gmat NEVER applies the principles of primes/factors/etc. to negative numbers. see below. --ron]
Ex.

N = -15
N/2 = -7.5

Prime factors of -15 are 3 and 5, both greater than -7.5

[RonPurewal]

please post the source of this question. if you don't, i'll delete it within the next week.

* NOTE *
DO NOT post another forum as the source of the question; "source" must refer to the original source. if the problem is from another forum and the original source is unknown to you, then we cannot accept the question here.

--

this problem is bad, anyway. really bad.
whatever the source is, set it on fire, run away as fast as you can, and don't look back.

statement (2) should be sufficient, unless you allow one of the following:
- negative numbers, as the previous poster said. the gmat doesn't do this. questions about primes/factors/etc are ALWAYS restricted to positive integers.
- "vacuously true" statements. i.e., statements that are true for "all the prime factors of N" because there are no prime factors of n. for instance, if n = 1, then n has no prime factors at all; hence ANY statement about those prime factors is automatically true. the gmat doesn't do this, either.