NEW HERE? LEARN MORE
closeclose
Last visit was: 23 Apr 2024, 22:40 It is currently 23 Apr 2024, 22:40
Decision Tracker
My Rewards
New posts
New comers' posts

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.
Go to My Error Log Learn more
Close
Request Expert Reply
Confirm Cancel

In how many ways can 8 girls be divided into 4 sets of 2 ?

User avatar
ajay_gmat
Intern
Intern
Joined: 14 Mar 2007
Posts: 42
Own Kudos [?]: 5 [0]
Given Kudos: 0
Send PM
In how many ways can 8 girls be divided into 4 sets of 2 ? [#permalink] New post   17 Jul 2007, 09:08
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

100% (00:05) correct 0% (00:00) wrong based on 0 sessions
Hide Show timer Statistics
In how many ways can 8 girls be divided into 4 sets of 2 ??



Archived Topic
Hi there,
This topic has been closed and archived due to inactivity or violation of community quality standards. No more replies are possible here.
Where to now? Join ongoing discussions on thousands of quality questions in our Problem Solving (PS) Forum
Still interested in this question? Check out the "Best Topics" block below for a better discussion on this exact question, as well as several more related questions.
Thank you for understanding, and happy exploring!
avatar
ishcabibble
Manager
Manager
Joined: 04 Aug 2005
Posts: 192
Own Kudos [?]: 10 [0]
Given Kudos: 0
Send PM
Re: In how many ways can 8 girls be divided into 4 sets of 2 ? [#permalink] New post   17 Jul 2007, 11:11
dahcrap, thanks for the answer, but could you elaborate a bit? Unfortunately, I'm one of those people where if I don't know how to do something I really don't know how to do it and kind of need it spelled out for me.

Especially since Comb. & Perm. are really a struggle for me, I'm trying to collect as many good problems and answers as possible. Thanks!
User avatar
dahcrap
Manager
Manager
Joined: 03 Jun 2007
Posts: 161
Own Kudos [?]: 26 [0]
Given Kudos: 0
Send PM
Re: In how many ways can 8 girls be divided into 4 sets of 2 ? [#permalink] New post   17 Jul 2007, 11:36
ishcabibble wrote:
dahcrap, thanks for the answer, but could you elaborate a bit? Unfortunately, I'm one of those people where if I don't know how to do something I really don't know how to do it and kind of need it spelled out for me.

Especially since Comb. & Perm. are really a struggle for me, I'm trying to collect as many good problems and answers as possible. Thanks!


This is actually a simple question though worded in a convulted manner. Just find the number of ways to select 4 people from a group of 8. This is 8C4. Now multiply the remainder by 4C4. Now lets take another example. How many ways can we form 3 groups of 4 from a group of 12 people ?

The answer is First choose 4 for the first group from 12. This 12C4. NOW CHOOSE the second group from the remaining 8. This give 8C4. Now finally choose the 4 from the remaining 4. This 4C4

So the answer is 12C4*8C4*4C4. Got it ?
User avatar
ajay_gmat
Intern
Intern
Joined: 14 Mar 2007
Posts: 42
Own Kudos [?]: 5 [0]
Given Kudos: 0
Send PM
Re: In how many ways can 8 girls be divided into 4 sets of 2 ? [#permalink] New post   18 Jul 2007, 00:44
The OA is 105. source: ps.zip from gmatclub forum.. Dont know how this answer came about :x
User avatar
sumande
Manager
Manager
Joined: 04 Jun 2007
Posts: 144
Own Kudos [?]: 81 [0]
Given Kudos: 0
Re: In how many ways can 8 girls be divided into 4 sets of 2 ? [#permalink] New post   18 Jul 2007, 00:53
ajay_gmat wrote:
In how many ways can 8 girls be divided into 4 sets of 2 ??


8 girls can be divided into 4 groups in 8!/[(8/4)!]^4 ways.

Imagine n distinct objects to be divided in p groups such that each contains (n/p) objects. This can be done in n!/[(n/p)!]^p ways.

Arrangements of the groups will not matter, hence, we have to divide the result by p!.

Thus, we have the required no. of ways = 8!/(2^4 * 4!) = 105. :-D
avatar
ishcabibble
Manager
Manager
Joined: 04 Aug 2005
Posts: 192
Own Kudos [?]: 10 [0]
Given Kudos: 0
Send PM
Re: In how many ways can 8 girls be divided into 4 sets of 2 ? [#permalink] New post   18 Jul 2007, 10:18
Thanks, dahcrap. Much appreciated!
User avatar
dahcrap
Manager
Manager
Joined: 03 Jun 2007
Posts: 161
Own Kudos [?]: 26 [0]
Given Kudos: 0
Send PM
Re: In how many ways can 8 girls be divided into 4 sets of 2 ? [#permalink] New post   18 Jul 2007, 10:48
dahcrap wrote:
ajay_gmat wrote:
In how many ways can 8 girls be divided into 4 sets of 2 ??

8C4 * 4C4


Oh Sorry I misunderstood the question as 2 sets of 4.

In this it is 8C2*6C2*4C2*2C2*4! whch equates to sumande's 8!/2^4 * 4!



Archived Topic
Hi there,
This topic has been closed and archived due to inactivity or violation of community quality standards. No more replies are possible here.
Where to now? Join ongoing discussions on thousands of quality questions in our Problem Solving (PS) Forum
Still interested in this question? Check out the "Best Topics" block above for a better discussion on this exact question, as well as several more related questions.
Thank you for understanding, and happy exploring!
GMAT Club Bot
gmatclubot
Re: In how many ways can 8 girls be divided into 4 sets of 2 ? [#permalink]
18 Jul 2007, 10:48
Moderators:
Bunuel
Math Expert
92883 posts
yashikaaggarwal
Senior Moderator - Masters Forum
3137 posts

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne
Main navigation
GMAT Resources
Partners
MBA Resources
www.gmac.com|www.mba.com | | GMAT Club Rules | Terms and Conditions