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

 It is currently 03 May 2015, 06:58

### 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

# combinations

 Question banks Downloads My Bookmarks Reviews Important topics
Author Message
TAGS:
Director
Joined: 17 Oct 2005
Posts: 940
Followers: 1

Kudos [?]: 62 [0], given: 0

combinations [#permalink]  25 Apr 2006, 09:29
just a refresher,

how many ways could you arrange the following letters? how do you approach these types agian? thanks
1)AABB

2)ABCDEF

3)AABBCC

4)AAB
Manager
Joined: 13 Dec 2005
Posts: 224
Location: Milwaukee,WI
Followers: 1

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

Re: combinations [#permalink]  25 Apr 2006, 09:42
joemama142000 wrote:
just a refresher,

how many ways could you arrange the following letters? how do you approach these types agian? thanks
1)AABB 4!/(2! *2!)

2)ABCDEF 6!

3)AABBCC 6! /(2! *2! *2!)

4)AAB3!/2!

to solve these kinds of problem first count the total no of alphabets say N and in the numerator put N! and if some of them are repeated r1 times , and some other r2 times ........divide the numerator by those factorial . so it becomes N!/(r1! *r2!)
Manager
Joined: 13 Dec 2005
Posts: 224
Location: Milwaukee,WI
Followers: 1

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

[#permalink]  25 Apr 2006, 10:07
joemama142000 wrote:
thanks ipc

you are always welcome .
Senior Manager
Joined: 24 Jan 2006
Posts: 254
Followers: 1

Kudos [?]: 3 [0], given: 0

[#permalink]  25 Apr 2006, 11:32
a real refresher .. indeed!
Director
Joined: 04 Jan 2006
Posts: 926
Followers: 1

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

[#permalink]  25 Apr 2006, 17:44
thanks a lot!

that was a good refresher!
GMAT Club Legend
Joined: 07 Jul 2004
Posts: 5078
Location: Singapore
Followers: 22

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

[#permalink]  25 Apr 2006, 17:56
1)AABB
Number of ways to arrange any 4 letters = 4!
But A and B are repeated, so we need to consider that there are going to be duplicates. The total number of ways is therefore 4!/2!2! = 6 ways

2)ABCDEF
The number of ways to arrange this is 6! simply because each letter is a different entity.

3)AABBCC
The way to approach this is the same as explained in 1. It's 6!/2!2!2! = 90 ways.

4)AAB
Same as for 3. Number of ways = 3!/2! = 3
[#permalink] 25 Apr 2006, 17:56
Similar topics Replies Last post
Similar
Topics:
Combinations 3 31 Mar 2010, 05:28
Combinations 4 21 Mar 2010, 21:03
2 Combinations 2 27 Oct 2009, 22:29
Combinations 6 05 Feb 2009, 17:48
1 COMBINATIONS 9 02 Feb 2009, 10:36
Display posts from previous: Sort by

# combinations

 Question banks Downloads My Bookmarks Reviews Important topics

 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®.