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Joined: 16 Oct 2010
Last visit: 07 Jul 2013
Posts: 65
Given Kudos: 3
Location: United States
Concentration: Finance, Entrepreneurship
Schools: INSEAD Jan '13 Kellogg 1YR '15 Sloan '16 IE '15
GMAT 1: 700 Q49 V35
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C
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Difficulty:
95%
(hard)
Question Stats:
22% (01:16) correct
78%
(00:57)
wrong
based on 208
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Date
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Not Attempted Yet
15 Jul 2012, 04:51
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Is x odd?
(1) 2x - 1 is odd --> \(2x-1=odd\) --> \(2x=even\) --> \(x=\frac{even}{2}\) --> \(x\) is an integer. Now, \(x=\frac{even}{2}\) could be even (consider \(x=\frac{even}{2}=\frac{4}{2}=2=even\)) as well as odd (consider \(x=\frac{even}{2}=\frac{2}{2}=1=odd\)). Not sufficient.
(2) x^3 is odd. If \(x=integer\) then in order \(x^3=odd\) to hold true, it must be odd (answer YES), but \(x\) could also be some irrational number, for example \(x=\sqrt[3]{5}\) (answer NO). Not sufficient.
(1)+(2) Since from (1) \(x=integer\) then from (2) we have that \(x=odd\). Sufficient.
Answer: C.
Hope it's clear.
(1) 2x - 1 is odd --> \(2x-1=odd\) --> \(2x=even\) --> \(x=\frac{even}{2}\) --> \(x\) is an integer. Now, \(x=\frac{even}{2}\) could be even (consider \(x=\frac{even}{2}=\frac{4}{2}=2=even\)) as well as odd (consider \(x=\frac{even}{2}=\frac{2}{2}=1=odd\)). Not sufficient.
(2) x^3 is odd. If \(x=integer\) then in order \(x^3=odd\) to hold true, it must be odd (answer YES), but \(x\) could also be some irrational number, for example \(x=\sqrt[3]{5}\) (answer NO). Not sufficient.
(1)+(2) Since from (1) \(x=integer\) then from (2) we have that \(x=odd\). Sufficient.
Answer: C.
Hope it's clear.
General Discussion
16 Jul 2012, 11:18
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@Bunuel:
I don't understand your approach for the first argument:
\(2x-1=odd\)
If the result muss be odd, so x must be even. It will be even if x is 2 or greater than 2. If x is odd the result won't be odd. If I say x = 1 so the result will be Zero. But Zero is neither even nor odd. So the satetement is sufficient ?
I don't understand your approach for the first argument:
\(2x-1=odd\)
If the result muss be odd, so x must be even. It will be even if x is 2 or greater than 2. If x is odd the result won't be odd. If I say x = 1 so the result will be Zero. But Zero is neither even nor odd. So the satetement is sufficient ?
