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M04 #02

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M04 #02 [#permalink]

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New post 21 Nov 2010, 06:37
Q: Is integer N even?
1. N^2 = N
2. N^3 = N

OA:
Statement (1) by itself is insufficient.
Statement (2) by itself is insufficient.
Statements (1) and (2) combined are insufficient. We know from S1 that the value of can be either 0 or 1. From S2, we have 1,0,-1 as possible values of . Combining the two statements does not tell us if is an even integer.
The correct answer is E.
==========
Why is not D? From both statements we know that N could be 0 or 1. We don't care which one exactly as long as N is not 2. Or, shall I assume that in GMAT tests ZERO is an even number?

Kudos [?]: 132 [0], given: 48

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Re: M04 #02 [#permalink]

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New post 21 Nov 2010, 06:46
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Vorskl wrote:
Q: Is integer N even?
1. N^2 = N
2. N^3 = N

OA:
Statement (1) by itself is insufficient.
Statement (2) by itself is insufficient.
Statements (1) and (2) combined are insufficient. We know from S1 that the value of can be either 0 or 1. From S2, we have 1,0,-1 as possible values of . Combining the two statements does not tell us if is an even integer.
The correct answer is E.
==========
Why is not D? From both statements we know that N could be 0 or 1. We don't care which one exactly as long as N is not 2. Or, shall I assume that in GMAT tests ZERO is an even number?


Zero is an even integer.

An even number is an integer that is "evenly divisible" by 2, i.e., divisible by 2 without a remainder.
An even number is an integer of the form \(n=2k\), where \(k\) is an integer.

So for \(k=0\) --> \(n=2*0=0\).

As for the question:

Is integer N even?

(1) N^2 = N --> \(n(n-1)=0\) --> either \(n=0=even\) or \(n=1=odd\). Not sufficient.
(2) N^3 = N --> \(n(n-1)(n+1)=0\) --> \(n=0=even\) or \(n=1=odd\) or \(n=-1=odd\). Not sufficient.

(1)+(2) \(n\) can still be zero, so even or 1, so odd. Not sufficient.

Answer: E.

For more on number properties check: math-number-theory-88376.html

Hope it helps.
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Kudos [?]: 129034 [2], given: 12187

Senior Manager
Senior Manager
User avatar
Status: Happy to join ROSS!
Joined: 29 Sep 2010
Posts: 273

Kudos [?]: 132 [0], given: 48

Concentration: General Management, Strategy
Schools: Ross '14 (M)
Reviews Badge
Re: M04 #02 [#permalink]

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New post 21 Nov 2010, 07:07
Ok, so ZERO is an even number or, more precisely, ZERO IS AN EVEN INTEGER.
That explains the question.
Thanks!

Kudos [?]: 132 [0], given: 48

Re: M04 #02   [#permalink] 21 Nov 2010, 07:07
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