Check GMAT Club Decision Tracker for the Latest School Decision Releases https://gmatclub.com/AppTrack

 It is currently 22 May 2017, 21:42

### 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

# pls explain this too...?? so much confused

 new topic post reply Question banks Downloads My Bookmarks Reviews Important topics
Author Message
TAGS:

### Hide Tags

Intern
Joined: 08 Mar 2011
Posts: 23
Followers: 0

Kudos [?]: 34 [0], given: 31

pls explain this too...?? so much confused [#permalink]

### Show Tags

09 Mar 2011, 04:29
can someone pls explain this concept..?
what do we mean by order does matter and order does not matter...??
for eg..) if we need to know the seating arrangement for 4 persons from 7 chairs,,,we take order matters and if we need to make a team of 4 people from 7 people in a room we take order not matters....??

or is there a better method to identify when order matters and when order does not matters...??
Director
Status: Impossible is not a fact. It's an opinion. It's a dare. Impossible is nothing.
Affiliations: University of Chicago Booth School of Business
Joined: 03 Feb 2011
Posts: 906
Followers: 14

Kudos [?]: 357 [2] , given: 123

Re: pls explain this too...?? so much confused [#permalink]

### Show Tags

09 Mar 2011, 04:46
2
KUDOS
There is a group of 7 people and 4 chairs are available. You want to seat 4, then the order matters
First chair can be filled in 7 ways
Second chair can be filled in 6 ways
Third chair can be filled in 5 ways
Fourth chair can be filled in 4 ways
Total ways = 7 * 6 * 5 * 4

On the other hand, if you are making a team of 4 from a group of 7, order does not matters. Its 7C4
A = First person can be chosen in 7 ways
B = Second person - 6 ways
C = Third person - 5 ways
D = Fourth person - 4 ways

But ABCD = BCDA = CDAB = DABA ..... etc
So you have duplicates. There will be 4! duplicates per selection

To make unique teams, you will have to divide by 4!
Hence no of ways = 7 * 6 * 5 * 4 / (4!) = 7C4

can someone pls explain this concept..?
what do we mean by order does matter and order does not matter...??
for eg..) if we need to know the seating arrangement for 4 persons from 7 chairs,,,we take order matters and if we need to make a team of 4 people from 7 people in a room we take order not matters....??

or is there a better method to identify when order matters and when order does not matters...??
Re: pls explain this too...?? so much confused   [#permalink] 09 Mar 2011, 04:46
Similar topics Replies Last post
Similar
Topics:
confusion with |x| 2 08 Nov 2013, 00:17
Confusing Percentages 0 21 Jul 2013, 21:50
1 I need too much time for DS questions 3 02 Jan 2012, 19:25
10 Geometry: Parallelogram Properties Explained 7 11 Dec 2016, 12:10
Confused Questions 6 27 Jan 2010, 10:50
Display posts from previous: Sort by

# pls explain this too...?? so much confused

 new topic post reply 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®.