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

It is currently 25 Oct 2014, 14:13

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

overlapping sets

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Manager
Manager
avatar
Joined: 31 Aug 2009
Posts: 58
Followers: 0

Kudos [?]: 6 [0], given: 0

overlapping sets [#permalink] New post 19 Sep 2009, 21:28
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

33% (01:26) correct 67% (01:42) wrong based on 13 sessions
According to a survey, at least 70% of people like apples, at least 75% like bananas and at least 80% like cherries. What is the minimum percentage of people who like all three?

A. 15%
B. 20%
C. 25%
D. 0%
E. 35%


I got this wrong. Here's my work. Where did I go wrong?

Let A&B&C = X

A&B (excl. C) = A+B-100-X = 45-X
B&C (excl. C)= B+C-100-X= 55-X
C&A (excl. C= C+A-100=50-X

Overlapping elements (ie everything that is in more than one set) = A+B+C - 100= 125

A&B+B&C+C&A+A&B&C= 125 => 45-x+55-x+50-x + x = 125. Solved it. Wrong answer.


Or Method 2:

A&B= A+B-100= 45
B&C= B+C-100=55
C&A= C+A-100= 50

Let X equal overlap of A&B&C

Overlapping elements (ie everything that is in more than one set) = A+B+C - 100= 125

A&B+B&C+C&A + (-3x+x) = 125

Since X is counted 3 times in the calculation above you need to take it out but you need 1 X that represent A&B&C thus:

A&B+B&C+C&A -2x = 125

Solving em. Wrong.
Director
Director
User avatar
Joined: 04 Jan 2008
Posts: 919
Followers: 53

Kudos [?]: 184 [0], given: 17

Re: overlapping sets [#permalink] New post 19 Sep 2009, 23:16
Manager
Manager
avatar
Joined: 31 Aug 2009
Posts: 58
Followers: 0

Kudos [?]: 6 [0], given: 0

Re: overlapping sets [#permalink] New post 20 Sep 2009, 00:14
thanks but i dont understand that solution. it is a very intuitive answer and i'm not at that level. i need some formulas. build from the ground up first then i'll try to understand it at a highlevel.

i guess A+B has to have some minimal overlap since it has to be max 100. But why not 40 or 35 etc.. because it only has to be less than 100 it doesn't have to add to 100.

unless you can explain that please feel free.
Manager
Manager
avatar
Joined: 15 Sep 2009
Posts: 139
Followers: 1

Kudos [?]: 16 [0], given: 2

Re: overlapping sets [#permalink] New post 20 Sep 2009, 04:17
I'm getting the min as 25.

I wud go with option C
Intern
Intern
avatar
Joined: 12 Aug 2009
Posts: 1
Followers: 0

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

Re: overlapping sets [#permalink] New post 15 Oct 2009, 01:46
70% like A
75% like B
80% like C

If 70% like A and 75% like B then the ones which like them both are 70+75-100 = 45%
80% like C so all the C lovers plus the ones which like A an B both are: 45+80 = 125
so the ones which like A + B + C are 125- 100= 25%
Manager
Manager
avatar
Joined: 16 May 2011
Posts: 205
Concentration: Finance, Real Estate
GMAT Date: 12-27-2011
WE: Law (Law)
Followers: 1

Kudos [?]: 30 [0], given: 37

GMAT ToolKit User
Re: overlapping sets [#permalink] New post 21 May 2011, 22:21
is using the formula correct:

100=70+75+80-(45+50+55)+all+ 0 ( neither)
all=100-75 hence 25%
VP
VP
avatar
Status: There is always something new !!
Affiliations: PMI,QAI Global,eXampleCG
Joined: 08 May 2009
Posts: 1364
Followers: 12

Kudos [?]: 144 [0], given: 10

Re: overlapping sets [#permalink] New post 23 May 2011, 22:21
so it goes

70+75 -100 = 45
45 + 80 -100 = 25 %
_________________

Visit -- http://www.sustainable-sphere.com/
Promote Green Business,Sustainable Living and Green Earth !!

Manager
Manager
User avatar
Joined: 05 Feb 2007
Posts: 141
Followers: 1

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

CAT Tests
Re: overlapping sets [#permalink] New post 25 May 2011, 17:49
amit2k9 wrote:
so it goes

70+75 -100 = 45
45 + 80 -100 = 25 %


So far the posts are just answers. Can anyone provide a solid explanation?
Re: overlapping sets   [#permalink] 25 May 2011, 17:49
    Similar topics Author Replies Last post
Similar
Topics:
2 Overlapping sets dimri10 6 13 Jun 2011, 03:47
5 overlapping sets ramana 7 21 Jul 2010, 01:43
Experts publish their posts in the topic Overlapping Sets Hussain15 7 15 Jul 2010, 23:45
overlapping sets indolent 3 10 Mar 2010, 04:28
Overlapping Sets MatiasMM 1 11 Sep 2009, 14:25
Display posts from previous: Sort by

overlapping sets

  Question banks Downloads My Bookmarks Reviews Important topics  


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®.