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

It is currently 21 Aug 2014, 04:45

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

m06 q14

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
Manager
Manager
User avatar
Joined: 02 Nov 2009
Posts: 95
Location: VA
Schools: Columbia Business School '13
WE 1: Investment Banking
WE 2: Higher Education
Followers: 2

Kudos [?]: 43 [0], given: 7

m06 q14 [#permalink] New post 04 Jan 2010, 19:34
What is the sum of a, b, and c?

1. a:b:c = 3:4:7

2. c-a = 12

Statements (1) and (2) combined are sufficient. Combining the two gives us the ratio between c and a. Thus if the difference between c and a is 12 and the difference in proportion is 4, then each of the proportions needs to be multiplied by 3 or (3+4+7)*3 = 42.

Can someone explain to me why you multiply by 3? I am not following the logic on this one.
_________________

My GMAT Debrief: my-gmat-experience-540-to-92850.html
Every man I meet is my superior in some way. In that, I learn of him. - Emerson

Manager
Manager
avatar
Joined: 29 Oct 2009
Posts: 57
Schools: Cambridge
Followers: 1

Kudos [?]: 9 [0], given: 14

Re: m06 q14 [#permalink] New post 04 Jan 2010, 22:49
phillypointgod21 wrote:
What is the sum of a, b, and c?

1. a:b:c = 3:4:7

2. c-a = 12

Statements (1) and (2) combined are sufficient. Combining the two gives us the ratio between c and a. Thus if the difference between c and a is 12 and the difference in proportion is 4, then each of the proportions needs to be multiplied by 3 or (3+4+7)*3 = 42.

Can someone explain to me why you multiply by 3? I am not following the logic on this one.


Philly,
I'll try to explain.
3, 4, 7 are ratio( of a number) . Let the original number be x.
So a = 3/14 of x; b = 4/14 of x and c = 7/14 of x.

Using stmt 2, c - a = 12 and above, we get (7/14 - 3/14)x = 12. Solving, 4x = 12*14, so x = 3* 14.
= > x = 42.
Sum has to be * by 3. ( ( 3+4+7) * 3)
I hope now its clear why we multiply by 3.

Cheers
_________________

No Execuse..

Intern
Intern
avatar
Joined: 07 Oct 2009
Posts: 33
Followers: 0

Kudos [?]: 3 [0], given: 1

Re: m06 q14 [#permalink] New post 05 Jan 2010, 10:45
Though aditya has given a good algebric explanation,here is another take.I hope it will also help u understand!

when u say a:b:c=3:4:7,it doesn't mean values of a,b,c are 3,4,7...It can be 3,4,7 or 6,8,14 or 9,12,21 and so on..It just means the simplest ratio between terms are in 3:4:7.

So stmt (1) alone is not sufficient.

c-a=12 doesnt tell us their values.So stmt(2) alone is not suffiient.

Combing these two, if we assume a,b,c are 9,12,21.these values satisfy both stmts, hence assumption is correct.

We get a,b,c as 9,12,21 by multiplying the ratio by 3. :)
Manager
Manager
User avatar
Joined: 02 Nov 2009
Posts: 95
Location: VA
Schools: Columbia Business School '13
WE 1: Investment Banking
WE 2: Higher Education
Followers: 2

Kudos [?]: 43 [0], given: 7

Re: m06 q14 [#permalink] New post 05 Jan 2010, 21:16
Thanks guys - both entries are helpful!
_________________

My GMAT Debrief: my-gmat-experience-540-to-92850.html
Every man I meet is my superior in some way. In that, I learn of him. - Emerson

Re: m06 q14   [#permalink] 05 Jan 2010, 21:16
    Similar topics Author Replies Last post
Similar
Topics:
8 Experts publish their posts in the topic m06 #06 mbaobsessed 10 12 Nov 2008, 13:39
9 Experts publish their posts in the topic m06 Q5 mbaobsessed 19 12 Nov 2008, 13:36
30 M06 #08 scthakur 26 04 Nov 2008, 00:59
1 M06 #19 dczuchta 6 24 Sep 2008, 20:16
Display posts from previous: Sort by

m06 q14

  Question banks Downloads My Bookmarks Reviews Important topics  

Moderators: Bunuel, WoundedTiger



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®.