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

 It is currently 22 May 2015, 22:00

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

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

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

Author Message
TAGS:
Manager
Joined: 14 Mar 2007
Posts: 62
Followers: 1

Kudos [?]: 1 [0], given: 0

In how many ways can 8 girls be divided into 4 sets of 2 ? [#permalink]  17 Jul 2007, 08:08
00:00

Difficulty:

(N/A)

Question Stats:

100% (01:05) correct 0% (00:00) wrong based on 0 sessions
In how many ways can 8 girls be divided into 4 sets of 2 ??
Manager
Joined: 04 Aug 2005
Posts: 202
Followers: 1

Kudos [?]: 5 [0], given: 0

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!
Senior Manager
Joined: 03 Jun 2007
Posts: 384
Followers: 2

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

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 ?
Manager
Joined: 14 Mar 2007
Posts: 62
Followers: 1

Kudos [?]: 1 [0], given: 0

The OA is 105. source: ps.zip from gmatclub forum.. Dont know how this answer came about
Senior Manager
Joined: 04 Jun 2007
Posts: 348
Followers: 1

Kudos [?]: 15 [0], given: 0

Re: PS : P & C Difficult Question [#permalink]  17 Jul 2007, 23:53
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.
Manager
Joined: 04 Aug 2005
Posts: 202
Followers: 1

Kudos [?]: 5 [0], given: 0

Thanks, dahcrap. Much appreciated!
Senior Manager
Joined: 03 Jun 2007
Posts: 384
Followers: 2

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

Re: PS : P & C Difficult Question [#permalink]  18 Jul 2007, 09:48
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!
Re: PS : P & C Difficult Question   [#permalink] 18 Jul 2007, 09:48
Similar topics Replies Last post
Similar
Topics:
5 In how many ways can 5 boys and 3 girls be seated on 8 5 24 Sep 2012, 12:02
In how many ways can a group of 8 be divided into 4 teams of 4 24 Aug 2007, 08:04
1 In how many ways can a group of 8 be divided into 4 teams of 9 22 Dec 2006, 21:37
How many different ways can a group of 8 be divided into 4 6 22 Jan 2006, 08:48
In how many ways can 8 boys be divided into two sets 2 25 Nov 2005, 16:25
Display posts from previous: Sort by