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

It is currently 20 Aug 2014, 14:57

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

What is the best approach here? I tryed the venn diagram,

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Manager
Manager
avatar
Joined: 24 Jun 2003
Posts: 94
Location: Moscow
Followers: 1

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

What is the best approach here? I tryed the venn diagram, [#permalink] New post 26 Jul 2003, 03:21
What is the best approach here? I tryed the venn diagram, but it did not help.

Q.
Each of three charities in East Side has 8 persons serving on its board of directors. If exactly 4 persons serve on 3 boards each and each pair of charities has 5 persons in common on their boards of directors, then how many distinct persons serve on one or more boards of directors?
_________________

Respect,

KL

SVP
SVP
User avatar
Joined: 03 Feb 2003
Posts: 1613
Followers: 5

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

 [#permalink] New post 26 Jul 2003, 03:44
employ a Venn diagram

A=8
B=8
C=8

ABC=4

if each pair of charities has 5 person in common, then this number includes those who serve in all the charities. Therefore, the number of people who serve in EXACTLY 2 charities is 1.

AB=1
BC=1
AC=1

N=8+8+8-1-1-1-2*4=13
Manager
Manager
avatar
Joined: 24 Jun 2003
Posts: 94
Location: Moscow
Followers: 1

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

 [#permalink] New post 26 Jul 2003, 03:52
Thanks, Stolyar.

I wrongly assumed the meaning of "each pair of charities has five persons in common" as 5 persons serving in each pair only and was stuck because the total number appeared negative.
_________________

Respect,

KL

Eternal Intern
User avatar
Joined: 07 Jun 2003
Posts: 480
Location: Lone Star State
Followers: 1

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

GMAT Tests User
 [#permalink] New post 26 Jul 2003, 08:09
"exactly 4 persons serve on 3 boards " kind of gives you the clue, the wording exactly is important. :lol:

So can I join you for some Starbucks Coffee with Lyn and Stolyar in Moscow :-D 8-)


N=8+8+8-1-1-1-2*4=13

Stolyar, I am not a math teacher but what is the formula stand for and how you get it. :roll:

N=8+8+8-1-1-1-2*4=13
- explain! :P [/quote]
SVP
SVP
User avatar
Joined: 03 Feb 2003
Posts: 1613
Followers: 5

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

 [#permalink] New post 26 Jul 2003, 10:41
imagine three overlapping circles. you need to find an area of this construction. BUT!!! you cannot simply add areas of the given circles. some areas overlap twice and one thrice. you have to eliminate these pieces in order not to count them many times.

So, we have to eliminate 'double' regions, and 'triple' region. In doing so, we 'clear' our construction from any overlapping.


AREA=A+B+C-exactly AB-exactly AC-exactly BC-2*ABC

The problem is much complicated when it comes to deal with four and more overlapping sets.

Last edited by stolyar on 26 Jul 2003, 12:12, edited 1 time in total.
Eternal Intern
User avatar
Joined: 07 Jun 2003
Posts: 480
Location: Lone Star State
Followers: 1

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

GMAT Tests User
 [#permalink] New post 26 Jul 2003, 11:56
Two triple regions is hard to see, but I think you mean three double regions, can you show your diagram to the Gmatworld.?
SVP
SVP
User avatar
Joined: 03 Feb 2003
Posts: 1613
Followers: 5

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

 [#permalink] New post 26 Jul 2003, 12:28
You should clearly understand what double and triple regions are. We have three double regions and one triple region.

Three double regions are counted twice. We need to count them only once; therefore, we need to subtract them from the sum.

The triple region is counted thrice. We need to subtract two times it from the sum.

To understand all this matter better, play with three paper circles. Overlap them, and cut them to have only one layer of paper throughout the whole construction.
  [#permalink] 26 Jul 2003, 12:28
    Similar topics Author Replies Last post
Similar
Topics:
venn diagram ?? fluke 6 18 Jul 2011, 12:13
1 venn diagram vcbabu 9 29 Jan 2009, 10:20
Venn Diagram el1981 4 13 Sep 2007, 09:47
venn diagram cejismundo 6 31 Aug 2006, 12:23
Display posts from previous: Sort by

What is the best approach here? I tryed the venn diagram,

  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®.