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B
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
15%
(low)
Question Stats:
79% (00:48) correct
21%
(00:48)
wrong
based on 132
sessions
History
Date
Time
Result
Not Attempted Yet
Is integer x odd?
(1) 2x + 1 is odd
(2) \(\frac{x}{2}\) is even
(1) 2x + 1 is odd
(2) \(\frac{x}{2}\) is even
OA uses testing cases as the strategy. I went a different method and got it wrong. I don't understand why my method is wrong.
(Statement 1) 2x + 1 is odd
2x + 1 = odd
2x = odd - 1
2x = even
x = \(\frac{even}{2}\)
x = even
x is even. Is x=odd? is definitely no, therefore SUFFICIENT
(Statement 2) \(\frac{x}{2}\) is even
\(\frac{x}{2} = even\)
\(x = (2) even\)
\(x = even\)
x is even. Is x=odd? is definitely no, therefore SUFFICIENT
Both answers are sufficient on their own. Answer D. I don't understand why my method is wrong. Why can't I use this method?
(Statement 1) 2x + 1 is odd
2x + 1 = odd
2x = odd - 1
2x = even
x = \(\frac{even}{2}\)
x = even
x is even. Is x=odd? is definitely no, therefore SUFFICIENT
(Statement 2) \(\frac{x}{2}\) is even
\(\frac{x}{2} = even\)
\(x = (2) even\)
\(x = even\)
x is even. Is x=odd? is definitely no, therefore SUFFICIENT
Both answers are sufficient on their own. Answer D. I don't understand why my method is wrong. Why can't I use this method?
0akshay0
Joined: 19 Apr 2016
Last visit: 14 Jul 2019
Posts: 192
Given Kudos: 59
Location: India
Schools: Jindal '20 Kelley '20 Broad '20 Carey '20 Mays '20
GMAT 1: 570 Q48 V22
GMAT 2: 640 Q49 V28
GPA: 3.5
WE:Web Development (Computer Software)
21 May 2017, 11:56
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KeithC517
KeithC517 : you went wrong at the highlighted part
2*Anything = Even
so Anything can be odd or even
In the highlighted part
x = even/2 even can be 4 or 6 so the corresponding values of x will be 2 or 3 --> thus x can be even or odd.
Hope it is clear
21 May 2017, 11:58
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KeithC517
Is integer x odd?
(1) 2x + 1 is odd
\(2x+1=odd\);
\(2x=odd-1=even\);
\(x=\frac{even}{2}\)
\(\frac{even}{2}\) can be even (for example 4/2) as well as odd (for example 2/2), so this statement is not sufficient.
(2) \(\frac{x}{2}\) is even
\(\frac{x}{2}=even\);
\(x=even*2=even\).
Sufficient.
Answer: B.
Hope its clear.
P.S. Highlighted part should answer your doubt.
