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Re: Question need help [#permalink]
10 Feb 2010, 12:42

Expert's post

Ekin4112 wrote:

If n is an integer is n even?

1) n^2-1 is an odd integer 2) 3n+4 is an even integer

According to GMAT answer it is D but I disagree and have to say it is E because n can be 0 which is not an even number while satisfying both requirement.

Any thoughts?

Hello Ekin, welcome to the Gmat Club.

First of all I must say that zero IS an even integer, though it's neither positive nor negative.

Even number (even integer) n is of the form n=2k, where k is an integer, so for k=0, n=2*0=0.

As for the question:

(1) n^2-1=(n-1)(n+1)=odd --> both n-1 and n+1 must be odd to produce an odd integer when multiplied, hence n is be even. Sufficient.

(2) 3n+4=even --> 3n must be even --> n must even. Sufficient.

Re: Question need help [#permalink]
14 Mar 2010, 02:12

Ekin4112 wrote:

If n is an integer is n even?

1) n^2-1 is an odd integer 2) 3n+4 is an even integer

According to GMAT answer it is D but I disagree and have to say it is E because n can be 0 which is not an even number while satisfying both requirement.

OFFICIAL GUIDE 12th Edition DS Q24 [#permalink]
10 Jun 2010, 23:27

If n is an integer, is n even? (1) (n^2) - 1 is an odd integer. (2) 3n + 4 is an even integer.

I personally think it is E, because putting n as 0, both the condition are insufficient. But the OA does not include 0 as one of the conditions to check.

Please explain or am I missing something here?

Thanks, Sandeep Nerli (Taking GMAT on 30th of June, 2010)

Re: OFFICIAL GUIDE 12th Edition DS Q24 [#permalink]
11 Jun 2010, 00:30

IMO A.

Why n=0 is not a valid condition?

sandeepnerli wrote:

If n is an integer, is n even? (1) (n^2) - 1 is an odd integer. (2) 3n + 4 is an even integer.

I personally think it is E, because putting n as 0, both the condition are insufficient. But the OA does not include 0 as one of the conditions to check.

Please explain or am I missing something here?

Thanks, Sandeep Nerli (Taking GMAT on 30th of June, 2010)

Re: OFFICIAL GUIDE 12th Edition DS Q24 [#permalink]
11 Jun 2010, 01:29

Hi,

The question clearly states that n is an integer, so n can be 0 and I agree that for n= 0 both the statements hold true, but since 0 is neither negative nor positive, I think the answer should be E, not D