Is a even? : GMAT Data Sufficiency (DS)
Check GMAT Club Decision Tracker for the Latest School Decision Releases http://gmatclub.com/AppTrack

 It is currently 16 Jan 2017, 07:32

### 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

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 a even?

 new topic post reply Question banks Downloads My Bookmarks Reviews Important topics
Author Message
TAGS:

### Hide Tags

Joined: 28 Mar 2012
Posts: 314
Location: India
GMAT 1: 640 Q50 V26
GMAT 2: 660 Q50 V28
GMAT 3: 730 Q50 V38
Followers: 29

Kudos [?]: 398 [1] , given: 23

Is a even? [#permalink]

### Show Tags

24 May 2012, 02:38
1
KUDOS
00:00

Difficulty:

5% (low)

Question Stats:

86% (01:24) correct 14% (00:31) wrong based on 267 sessions

### HideShow timer Statistics

Is a even?

(1) 2a is even.
(2) $$\sqrt{a}$$ is even.
[Reveal] Spoiler: OA

Last edited by Bunuel on 15 Jul 2013, 23:06, edited 2 times in total.
Edited the OA.
Math Expert
Joined: 02 Sep 2009
Posts: 36509
Followers: 7064

Kudos [?]: 92881 [0], given: 10528

Re: Is a even? [#permalink]

### Show Tags

24 May 2012, 02:44
Expert's post
1
This post was
BOOKMARKED
Is a even?

(1) 2a is even --> a can be even as well as odd. Not sufficient.

(2) $$\sqrt{a}$$ is even --> $$\sqrt{a}=even$$ --> $$a=even^2=even$$. Sufficient.

_________________
Joined: 28 Mar 2012
Posts: 314
Location: India
GMAT 1: 640 Q50 V26
GMAT 2: 660 Q50 V28
GMAT 3: 730 Q50 V38
Followers: 29

Kudos [?]: 398 [0], given: 23

Re: Is a even? [#permalink]

### Show Tags

24 May 2012, 02:58
Hi,

My mistake, option two needs to be corrected as $$a^2$$, in that case the answer is E.

Regards,
Math Expert
Joined: 02 Sep 2009
Posts: 36509
Followers: 7064

Kudos [?]: 92881 [2] , given: 10528

Re: Is a even? [#permalink]

### Show Tags

24 May 2012, 03:16
2
KUDOS
Expert's post
1
This post was
BOOKMARKED
Hi,

My mistake, option two needs to be corrected as $$a^2$$, in that case the answer is E.

Regards,

No, in this case the answer would be C.

Is a even?

(1) 2a is even --> $$2a=even$$ --> $$a=\frac{even}{2}$$, so $$a$$ is either even or odd (in any case $$a$$ must be an integer). Not sufficient.

(2) $$a^2$$ is even --> $$a^2=even$$ --> $$a=\sqrt{even}$$, so $$a$$ is either even (for example if $$a^2=4$$) or an irrational number (for example if $$a^2=6$$). Not sufficient. Generally $$a^2$$ to be an integer $$a$$ must be either an integer or an irrational number (for example: $$\sqrt{3}$$), (notice that $$a$$ can not be reduced fraction, for example $$\frac{2}{3}$$ or $$\frac{11}{3}$$ as in this case $$a^2$$ won't be an integer).

(1)+(2) Since from (1) $$a$$ is an integer, then in order $$a^2$$ to be even $$a$$ must be even too. Sufficient.

Hope it's clear.
_________________
Joined: 28 Mar 2012
Posts: 314
Location: India
GMAT 1: 640 Q50 V26
GMAT 2: 660 Q50 V28
GMAT 3: 730 Q50 V38
Followers: 29

Kudos [?]: 398 [0], given: 23

Re: Is a even? [#permalink]

### Show Tags

24 May 2012, 04:18
Thanks for the clarification!
Senior Manager
Joined: 28 Dec 2010
Posts: 334
Location: India
Followers: 1

Kudos [?]: 199 [0], given: 33

Re: Is a even? [#permalink]

### Show Tags

24 May 2012, 08:03
for the incorrect problem picked B. great explanation by bunuel of the original problem. especially liked the representation of expression such as even/2. makes analysis much simpler.
Math Expert
Joined: 02 Sep 2009
Posts: 36509
Followers: 7064

Kudos [?]: 92881 [0], given: 10528

Re: Is a even? [#permalink]

### Show Tags

12 Jun 2013, 03:27
Bumping for review and further discussion*. Get a kudos point for an alternative solution!

*New project from GMAT Club!!! Check HERE

Theory on Number Properties: math-number-theory-88376.html

All DS Number Properties Problems to practice: search.php?search_id=tag&tag_id=38
All PS Number Properties Problems to practice: search.php?search_id=tag&tag_id=59

_________________
Manager
Joined: 28 Feb 2012
Posts: 115
Concentration: Strategy, International Business
Schools: INSEAD Jan '13
GPA: 3.9
WE: Marketing (Other)
Followers: 0

Kudos [?]: 42 [1] , given: 17

Re: Is a even? [#permalink]

### Show Tags

12 Jun 2013, 22:05
1
KUDOS
Is a even?

(1) 2a is even.
(2) $$\sqrt{a}$$ is even.

(1) we need to remember that when whatever (even odd numbers) numbers are multiplied by 2 the result will be an even number. In the first statement a could be odd, so the statement is not sufficient;

(2) if $$\sqrt{a}$$ is even that means that a consists of at least two identical factors and that factor is even. Since that two identical factors are similar then their product (in this case it is a) must be even as well. So this statement is sufficient. Answer is B
_________________

If you found my post useful and/or interesting - you are welcome to give kudos!

Manager
Joined: 20 Oct 2013
Posts: 66
Followers: 0

Kudos [?]: 2 [0], given: 27

Re: Is a even? [#permalink]

### Show Tags

04 May 2014, 03:46
Hi Bunnel

i didnt understand the explanation for st 2 in revised qs.

(2) a^2 is even --> a^2=even --> a=\sqrt{even}, so a is either even (for example if a^2=4) or an irrational number (for example if a^2=6). Sufficient. Generally a^2 to be an integer a must be either an integer or an irrational number (for example: \sqrt{3}), (notice that a can not be reduced fraction, for example \frac{2}{3} or \frac{11}{3} as in this case a^2 won't be an integer).

the qs is asking if a is even... if a^2 = 6... then also a is even right? as the qs doesnt mention integer anywhere.
_________________

Hope to clear it this time!!
GMAT 1: 540
Preparing again

Math Expert
Joined: 02 Sep 2009
Posts: 36509
Followers: 7064

Kudos [?]: 92881 [0], given: 10528

Re: Is a even? [#permalink]

### Show Tags

04 May 2014, 04:04
nandinigaur wrote:
Hi Bunnel

i didnt understand the explanation for st 2 in revised qs.

(2) a^2 is even --> a^2=even --> a=\sqrt{even}, so a is either even (for example if a^2=4) or an irrational number (for example if a^2=6). Not sufficient. Generally a^2 to be an integer a must be either an integer or an irrational number (for example: \sqrt{3}), (notice that a can not be reduced fraction, for example \frac{2}{3} or \frac{11}{3} as in this case a^2 won't be an integer).

the qs is asking if a is even... if a^2 = 6... then also a is even right? as the qs doesnt mention integer anywhere.

Don't follow you... If $$a^2=6$$, then $$a=\sqrt{6}\neq{integer}$$.
_________________
Manager
Joined: 20 Oct 2013
Posts: 66
Followers: 0

Kudos [?]: 2 [0], given: 27

Re: Is a even? [#permalink]

### Show Tags

04 May 2014, 04:19
i mean to say that a=sqrt 6 is even right? how do we know that it has to be an interger.
_________________

Hope to clear it this time!!
GMAT 1: 540
Preparing again

Manager
Joined: 20 Oct 2013
Posts: 66
Followers: 0

Kudos [?]: 2 [0], given: 27

Re: Is a even? [#permalink]

### Show Tags

04 May 2014, 04:29
oh i get it... we can classify only integers as odd or even... irrational numbers cannot be even or odd.. so when we say a sqrt6... is it an irrational number which cannot be even or odd. am i right?

"key take away": only integers can be odd or even right?
_________________

Hope to clear it this time!!
GMAT 1: 540
Preparing again

Math Expert
Joined: 02 Sep 2009
Posts: 36509
Followers: 7064

Kudos [?]: 92881 [0], given: 10528

Re: Is a even? [#permalink]

### Show Tags

04 May 2014, 05:06
nandinigaur wrote:
oh i get it... we can classify only integers as odd or even... irrational numbers cannot be even or odd.. so when we say a sqrt6... is it an irrational number which cannot be even or odd. am i right?

"key take away": only integers can be odd or even right?

Yes, only integers can be even or odd:

An even number is an integer that is "evenly divisible" by 2, i.e., divisible by 2 without a remainder.

An odd number is an integer that is not evenly divisible by 2.

Theory on Number Properties: math-number-theory-88376.html

All DS Number Properties Problems to practice: search.php?search_id=tag&tag_id=38
All PS Number Properties Problems to practice: search.php?search_id=tag&tag_id=59

Hope this helps.
_________________
GMAT Club Legend
Joined: 09 Sep 2013
Posts: 13412
Followers: 575

Kudos [?]: 163 [0], given: 0

Re: Is a even? [#permalink]

### Show Tags

07 Jan 2017, 07:22
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________
Re: Is a even?   [#permalink] 07 Jan 2017, 07:22
Similar topics Replies Last post
Similar
Topics:
Is n an even? 3 10 Jan 2017, 18:42
6 Is P even? 3 22 Oct 2016, 06:05
12 Is a an even integer? 7 09 Feb 2015, 05:35
Is the integer a even? 2 18 Aug 2014, 02:34
13 Is z even? 17 04 May 2011, 23:27
Display posts from previous: Sort by

# Is a even?

 new topic post reply 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®.