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

It is currently 25 Oct 2014, 16:42

Close

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

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

factors of 12 are 3,2,2 If i understand correctly, if 3 , 2

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
1 KUDOS received
Manager
Manager
User avatar
Joined: 08 Sep 2010
Posts: 59
Followers: 0

Kudos [?]: 7 [1] , given: 4

GMAT ToolKit User
factors of 12 are 3,2,2 If i understand correctly, if 3 , 2 [#permalink] New post 20 Jun 2011, 06:55
1
This post received
KUDOS
00:00
A
B
C
D
E

Difficulty:

  5% (low)

Question Stats:

17% (00:00) correct 83% (01:13) wrong based on 6 sessions
factors of 12 are 3,2,2

If i understand correctly, if 3 , 2 are factors of 12. certain multiples of 3,2 will also be factors of 12 because you are going up or down a factor tree.

so 2k + 3m = t

even without reading the statements, doesn't the equation above say that t and 12 have 3,2 as common factors simply because those numbers are being multiplied to make t?
[Reveal] Spoiler: OA

Attachments

divisibility5-a.png
divisibility5-a.png [ 22.4 KiB | Viewed 1252 times ]


_________________

Don't forget to give me ****KUDOS****
;)

Manager
Manager
User avatar
Joined: 08 Sep 2010
Posts: 59
Followers: 0

Kudos [?]: 7 [0], given: 4

GMAT ToolKit User
Re: divisibility & primes [#permalink] New post 20 Jun 2011, 07:21
nvm....figured it out....ill post for those wondering....

if it was like 2k=t or 3m=t, then yes t and 12 would have factors 2,3 accordingly.

but since 2k and 3m are being added, you cannot simply say they 2,3 themselves can be the factors but the factors will be generated by the SUM of the multiples of 2 and 3 here.
_________________

Don't forget to give me ****KUDOS****
;)

Manager
Manager
avatar
Joined: 07 Jun 2011
Posts: 76
Followers: 0

Kudos [?]: 9 [0], given: 31

Re: divisibility & primes [#permalink] New post 07 Aug 2011, 18:30
Are you sure the answer is A? if so could you please post the explanation that was provided along with the question.
Director
Director
User avatar
Status:
Joined: 24 Jul 2011
Posts: 557
GMAT 1: 780 Q51 V48
GRE 1: 1540 Q800 V740
Followers: 64

Kudos [?]: 288 [0], given: 11

Re: divisibility & primes [#permalink] New post 07 Aug 2011, 19:48
The answer should be (A).

By simplifying the equation we get 2k + 3m = t
Does this mean that 2 and/or 3 are factors of t? Not necessarily!
Consider k=1 and m=1 => t=5. Does t have 2 and 3 as factors? No!
Alternately, consider k=3 and m=2 => t=12. In this case, t does have both k and m as factors.

Point to note:
If a positive integer is the sum of the multiples of other positive integers, it need not be a multiple of either of the integers!

Carrying on with this question,

Using statement 1: If k is a multiple of 3, then the equation can be written as
2k + 3m = t
=> 2*3n + 3m = t (where n is a positive integer)
=> 3 (2n +m) = t
=> 3 is a factor of t
=> t and 12 have a common factor greater than 1 (i.e. 3)
SUFFICIENT.

Consider statement 2: If m is a multiple of 3, we can write the equation as
2k + 3m = t
=> 2k + 3*3n = t (where n is a positive integer)
=> 2k + 9n = t
If we take n=1 and k=3, we get t=15, which has 3 as a common factor greater than 1 with 12
If we take k=1 and n=1, we get t=11, which has no common factor greater than 1 with 12
Therefore statement 2 alone is insufficient.

The answer is (A).
_________________

GyanOne | http://www.GyanOne.com | +91 9899831738

Get a free detailed MBA profile evaluation

Top MBA Rankings and MBA Admissions blog


Image

Re: divisibility & primes   [#permalink] 07 Aug 2011, 19:48
    Similar topics Author Replies Last post
Similar
Topics:
Experts publish their posts in the topic If (2/3)^n=(3/2)^2, what is the value of n? jsphcal 4 16 Jun 2012, 19:47
1 Experts publish their posts in the topic Sequence S is defined as follows: S1=2, S2=2^1, S3=2^2, SN=2 BN1989 3 21 Mar 2012, 04:18
Diagnostic Test: Match Q12. I Dont understand it Kingsintown 1 20 Jul 2011, 02:14
I'm not sure if I understand this q correctly... Alaska Richardson 8 24 Sep 2008, 18:50
GMATPrep2 hard questions I could not answer correctly,>70 techieGuy 12 06 Aug 2006, 17:40
Display posts from previous: Sort by

factors of 12 are 3,2,2 If i understand correctly, if 3 , 2

  Question banks Downloads My Bookmarks Reviews Important topics  


cron

GMAT Club MBA Forum Home| About| Privacy Policy| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

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®.