Find all School-related info fast with the new School-Specific MBA Forum

 It is currently 06 May 2015, 00:03

GMAT Club Daily Prep

Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

Is x odd?

 Question banks Downloads My Bookmarks Reviews Important topics
Author Message
TAGS:
Manager
Joined: 16 Oct 2010
Posts: 89
Location: United States
Concentration: Finance, Entrepreneurship
GMAT 1: 700 Q49 V35
WE: Information Technology (Investment Banking)
Followers: 0

Kudos [?]: 28 [0], given: 3

Is x odd? [#permalink]  15 Jul 2012, 03:30
00:00

Difficulty:

75% (hard)

Question Stats:

12% (01:19) correct 88% (00:40) wrong based on 25 sessions
Is x odd?

(1) 2x - 1 is odd
(2) x^3 is odd
[Reveal] Spoiler: OA

Last edited by Bunuel on 15 Jul 2012, 03:41, edited 1 time in total.
Edited the question.
Math Expert
Joined: 02 Sep 2009
Posts: 27228
Followers: 4231

Kudos [?]: 41112 [2] , given: 5666

Re: Is x odd? [#permalink]  15 Jul 2012, 03:51
2
This post received
KUDOS
Expert's post
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.
_________________
Intern
Joined: 19 Apr 2012
Posts: 28
Followers: 0

Kudos [?]: 3 [0], given: 8

Re: Is x odd? [#permalink]  16 Jul 2012, 10:18
@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 ?
Math Expert
Joined: 02 Sep 2009
Posts: 27228
Followers: 4231

Kudos [?]: 41112 [0], given: 5666

Re: Is x odd? [#permalink]  16 Jul 2012, 12:06
Expert's post
Alexmsi wrote:
@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 ?

Several things:

1. $$2x-1=odd$$ --> $$2x=odd+1=odd+odd=even$$ --> so $$2x=even$$ --> $$x=\frac{even}{2}=integer$$. Hence $$2x-1=odd$$ just means that $$x$$ is an integer (it can be even as well as odd).

2. If $$x=1$$the result wont be zero, it'l be 1, so odd: $$2*1-1=2-1=1=odd$$.

3. Zero is an even integer. Zero is nether positive nor negative, but zero is definitely an even number.

An even number is an integer that is "evenly divisible" by 2, i.e., divisible by 2 without a remainder and as zero is evenly divisible by 2 then it must be even (in fact zero is divisible by every integer except zero itself).

Or in another way: an even number is an integer of the form $$n=2k$$, where $$k$$ is an integer. So for $$k=0$$ --> $$n=2*0=0$$.

Hope it's clear.
_________________
Re: Is x odd?   [#permalink] 16 Jul 2012, 12:06
Similar topics Replies Last post
Similar
Topics:
1 Is the positive integer x odd? 2 21 Oct 2014, 08:10
8 Is x an odd number? 10 28 Feb 2013, 06:23
1 Is x an odd integer? 2 02 Nov 2012, 03:15
Is X^3 an odd integer? (1) 3 square root X is an odd 5 21 Aug 2007, 04:38
Is integer x odd? 6 20 Feb 2007, 18:09
Display posts from previous: Sort by

Is x odd?

 Question banks Downloads My Bookmarks Reviews Important topics

 Powered by phpBB © phpBB Group and phpBB SEO Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.