Find all School-related info fast with the new School-Specific MBA Forum
Learn more about the recent changes... close

It is currently 24 May 2013, 14:47
Customize  |  Hide

Search
Register
New posts
Unanswered

unique teams

  Question banks Downloads My Bookmarks Reviews  
  Oldest Best Reply
Search for:
 
Print view
First unread post
Author Message
TAGS:
Manager
Manager
User avatar
Status: Still Struggling
Joined: 03 Nov 2010
Posts: 142
Location: India
GMAT Date: 10-15-2011
GPA: 3.71
WE: Information Technology (Computer Software)
Followers: 3

Kudos [?]: 24 [0], given: 8

unique teams [#permalink] New post 16 Dec 2010, 01:40
00:00

Question Stats:

0% (00:00) correct 100% (04:01) wrong based on 0 sessions
There are 12 co-workers who work on projects in teams each month. Each team is comprised of 3 people and every team is together only once before the rotation begins again. How many unique teams can be created?

My effort:
From the above scenario, it is clear that there are 4 teams and each comprises of 3 people.
Hence, i took m=4 and n=3 in the formula (mn)! / (n!)^m * m!

but the answer coming is wrong. Can somebody please tell me whats wrong in here?

OA : 220
_________________

Appreciation in KUDOS please!
Knewton Free Test 10/03 - 710 (49/37)
Princeton Free Test 10/08 - 610 (44/31)
Kaplan Test 1- 10/10 - 630
Veritas Prep- 10/11 - 630 (42/37)
MGMAT 1 - 10/12 - 680 (45/34)

Kaplan GMAT Instructor
User avatar
Joined: 21 Jun 2010
Posts: 148
Location: Toronto
Followers: 31

Kudos [?]: 89 [0], given: 0

Re: unique teams [#permalink] New post 16 Dec 2010, 02:10
krishnasty wrote:
There are 12 co-workers who work on projects in teams each month. Each team is comprised of 3 people and every team is together only once before the rotation begins again. How many unique teams can be created?

My effort:
From the above scenario, it is clear that there are 4 teams and each comprises of 3 people.
Hence, i took m=4 and n=3 in the formula (mn)! / (n!)^m * m!

but the answer coming is wrong. Can somebody please tell me whats wrong in here?

OA : 220


Hi!

You've vastly overcomplicated the problem.

The simplest interpretation of the question is "how many unique groups of 3 people can be made out of a total pool of 12?"

The answer is then 12C3. Plugging into the combinations formula:

12C3 = 12!/3!9! = 12*11*10/3*2*1 = 2*11*10 = 220

To be honest, I'm not even sure where they formula you used comes from - I've never seen it before.
_________________

Stuart Kovinsky
stuart.kovinsky@kaplan.com
Kaplan Test Prep & Admissions
Toronto Office
1-800-KAP-TEST
http://www.kaptest.com/GMAT

Prepare with Kaplan and save $150 on a course!

Image

Kaplan Reviews

Manager
Manager
User avatar
Status: Still Struggling
Joined: 03 Nov 2010
Posts: 142
Location: India
GMAT Date: 10-15-2011
GPA: 3.71
WE: Information Technology (Computer Software)
Followers: 3

Kudos [?]: 24 [0], given: 8

Re: unique teams [#permalink] New post 16 Dec 2010, 04:16
well, that seemed a very easy approach to do so..

The formula that i have used was posted by Bunuel in some of his post. And to tell you the truth, i have often used this formula to derive the correct answer..

@Bunuel, can you please point out if i used the formula incorrectly or where exactly i made a mistake.

Thanks Guys!!
_________________

Appreciation in KUDOS please!
Knewton Free Test 10/03 - 710 (49/37)
Princeton Free Test 10/08 - 610 (44/31)
Kaplan Test 1- 10/10 - 630
Veritas Prep- 10/11 - 630 (42/37)
MGMAT 1 - 10/12 - 680 (45/34)

Manager
Manager
Joined: 02 Apr 2010
Posts: 103
Followers: 2

Kudos [?]: 76 [0], given: 18

Re: unique teams [#permalink] New post 16 Dec 2010, 04:32
I agree with skovinsky that the solution is simply 12!/(9!*3!) = 220.

I've studied quite a lot of combinatorics for my GMAT and I've never come across the formula you listed above. It looks too fancy to be relevant for the GMAT :) . For the GMAT it's enough to remember just the basic formulas for combinations and permutations. If you understand these formulas and know how to apply them you should be able to answer pretty much all the questions.
GMAT Club team member
User avatar
Joined: 02 Sep 2009
Posts: 11610
Followers: 1801

Kudos [?]: 9594 [0], given: 829

GMAT Tests User CAT Tests
Top Member of the Month
Re: unique teams [#permalink] New post 16 Dec 2010, 06:34
krishnasty wrote:
well, that seemed a very easy approach to do so..

The formula that i have used was posted by Bunuel in some of his post. And to tell you the truth, i have often used this formula to derive the correct answer..

@Bunuel, can you please point out if i used the formula incorrectly or where exactly i made a mistake.

Thanks Guys!!


As OA given to be 220 then skovinsky's interpretation of the question is correct and the answer is simply 12C3=220.

You are applying the formula of dividing a group of people (items) equally into smaller groups when order matters, but it's not the case here, as we don't have 4 projects to make 4 groups of 3 to assign to them. Note that even in this case you can solve the question without this formula, for more on this check:

probability-88685.html?hilit=different%20items%20divided%20equally
probability-85993.html?highlight=divide+groups
combination-55369.html#p690842
sub-committee-86346.html?highlight=divide+groups
combination-and-selection-into-team-106277.html

Hope it's clear.
_________________

PLEASE READ AND FOLLOW: 11 Rules for Posting!!!

RESOURCES: [GMAT MATH BOOK]; 1. Triangles; 2. Polygons; 3. Coordinate Geometry; 4. Factorials; 5. Circles; 6. Number Theory

COLLECTION OF QUESTIONS:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. NEW!!!

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS ; 9 Devil's Dozen!!!; 10 Number Properties set. NEW!!!


What are GMAT Club Tests?
25 extra-hard Quant Tests

Find out what's new at GMAT Club - latest features and updates

Re: unique teams   [#permalink] 16 Dec 2010, 06:34
    Similar topics Author Replies Last post
Similar
Topics:
 New posts Unique Essays Jennif102 4 19 Sep 2005, 20:29
New posts 1 Unique ECs pguard 8 22 Dec 2008, 13:01
New posts 1 Teams bibha 5 07 Aug 2010, 22:34
New posts Team Derek1988 6 06 Jan 2011, 08:13
New posts 1 Unique shanek 2 22 Apr 2013, 08:37
Display posts from previous: Sort by

unique teams

  Question banks Downloads My Bookmarks Reviews  
Print view
First unread post

Moderators: Bunuel, VeritasPrepKarishma, IanStewart

Search for:


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®.

Main navigation

GMAT Resources

Partners

MBA Resources

www.gmac.com|www.mba.com