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# PS-Must Be True- 2

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Director
Joined: 04 Jan 2008
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PS-Must Be True- 2 [#permalink]  01 Apr 2009, 01:13
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Question Stats:

100% (02:22) correct 0% (00:00) wrong based on 0 sessions
If a and b are both even non-zero integers, which of the following must be true?

A) The product of a and b is odd

B) The sum of a and b is odd

C) a - b > 0

D) a raised to the b power is even

E) (a + b)/4 is even

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Joined: 13 Jan 2009
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Re: PS-Must Be True- 2 [#permalink]  01 Apr 2009, 15:45

If you give a and b are positive integers then D will be true else all choices are wrong.

I can prove C D and E true if question changes to could be true instead of must be true.
Director
Joined: 04 Jan 2008
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Kudos [?]: 244 [0], given: 17

Re: PS-Must Be True- 2 [#permalink]  02 Apr 2009, 02:20
OE says

It's easiest to find examples that prove the other four choices wrong. For answers A, B, and C, choosing a=2 and b=4 makes the statements incorrect. For answer E, choosing a=4 and b=8 makes the statement false. Answer D is the only one that holds true always.

thx
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Re: PS-Must Be True- 2 [#permalink]  02 Apr 2009, 06:11
nitya34 wrote:
OE says

It's easiest to find examples that prove the other four choices wrong. For answers A, B, and C, choosing a=2 and b=4 makes the statements incorrect. For answer E, choosing a=4 and b=8 makes the statement false. Answer D is the only one that holds true always.

thx

Either the OE is wrong, or there's a word missing from the question. What's the source? D certainly must be true *if* a and b are *positive* even integers. The question (as posted) only says that they are 'non-zero', which means they could be negative. If a = 2, and b = -2, then a^b = 1/4, and is not an integer, so certainly is not even.
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Intern
Joined: 29 Dec 2006
Posts: 32
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Kudos [?]: 0 [0], given: 0

Re: PS-Must Be True- 2 [#permalink]  15 Apr 2009, 15:36
it's funny how i automatically assumed the numbers are positive. is that word supposed to be in the question? also, just for my fyi, what does oe stand for?
Manager
Joined: 14 Nov 2008
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Schools: Stanford...Wait, I will come!!!
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Re: PS-Must Be True- 2 [#permalink]  16 Apr 2009, 04:27
OE = Offical Explanation
gmat911 wrote:
it's funny how i automatically assumed the numbers are positive. is that word supposed to be in the question? also, just for my fyi, what does oe stand for?
Senior Manager
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Re: PS-Must Be True- 2 [#permalink]  16 Apr 2009, 08:59
I also think it's a bad question.
Either the word "positive" in the question stem, or another answer choice 'none' is missing.
Re: PS-Must Be True- 2   [#permalink] 16 Apr 2009, 08:59
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