A quick question on fractions: why THIS and not THAT? : GMAT Quantitative Section
Check GMAT Club Decision Tracker for the Latest School Decision Releases http://gmatclub.com/AppTrack

 It is currently 23 Jan 2017, 04:42

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

A quick question on fractions: why THIS and not THAT?

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

Hide Tags

Manager
Joined: 12 Jan 2013
Posts: 244
Followers: 4

Kudos [?]: 69 [0], given: 47

A quick question on fractions: why THIS and not THAT? [#permalink]

Show Tags

06 Jul 2013, 02:17
Hi fellow b-school aspirants, veterans and GMAT scholars

Ive just started my GMAT mission, and am currently reading MGMATs Foundations of Math. In the fractions chapter, there are several problems at the end. There is one problem that goes like this:

Quote:
Multiply or divide the following fractions. Fractions should be in their most simplified form

7/(n+3) * (n+1)/2

The OA is (7n+7)/(2n+6) , but why cant we simplify that expression further, by cancelling 7n by 2n, making it 5n, and cancelling 7 by 6, making it 1,and thus we have the answer 5n + 1?

I understand theres a flaw in my knowledge of concept, is the reason this cancelling operation is illegal because we're dealing with addition as opposed to multiplication, or is there some other explanation?
Math Expert
Joined: 02 Sep 2009
Posts: 36609
Followers: 7099

Kudos [?]: 93508 [1] , given: 10568

Re: A quick question on fractions: why THIS and not THAT? [#permalink]

Show Tags

06 Jul 2013, 02:42
1
This post received
KUDOS
Expert's post
aeglorre wrote:
Hi fellow b-school aspirants, veterans and GMAT scholars

Ive just started my GMAT mission, and am currently reading MGMATs Foundations of Math. In the fractions chapter, there are several problems at the end. There is one problem that goes like this:

Quote:
Multiply or divide the following fractions. Fractions should be in their most simplified form

7/(n+3) * (n+1)/2

The OA is (7n+7)/(2n+6) , but why cant we simplify that expression further, by cancelling 7n by 2n, making it 5n, and cancelling 7 by 6, making it 1,and thus we have the answer 5n + 1?

I understand theres a flaw in my knowledge of concept, is the reason this cancelling operation is illegal because we're dealing with addition as opposed to multiplication, or is there some other explanation?

We have $$\frac{7n+7}{2n+6}$$: (7n+7) is divided by (2n+6). This is not the same as subtraction: $$(7n+7)-(2n+6)=5n+1$$.

Hope it's clear.
_________________
Manager
Joined: 12 Jan 2013
Posts: 244
Followers: 4

Kudos [?]: 69 [0], given: 47

Re: A quick question on fractions: why THIS and not THAT? [#permalink]

Show Tags

06 Jul 2013, 03:52
Thank you, the way you put it makes it much clearer than the books explanation.
Re: A quick question on fractions: why THIS and not THAT?   [#permalink] 06 Jul 2013, 03:52
Similar topics Replies Last post
Similar
Topics:
4 Why You Should Convert Fractions to Decimals on the GMAT 0 17 Dec 2014, 06:03
A quick question about fractions 1 13 Sep 2013, 02:16
A quick question about Inequalities 3 10 Sep 2013, 02:36
A quick question 0 09 Jul 2010, 08:36
1 Fractions GMAT Questions - Master List 2 19 Jun 2009, 18:25
Display posts from previous: Sort by

A quick question on fractions: why THIS and not THAT?

 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®.