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

It is currently 25 Jul 2014, 06:03

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.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

Probability

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Senior Manager
Senior Manager
avatar
Joined: 11 Nov 2003
Posts: 356
Location: Illinois
Followers: 1

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

GMAT Tests User
Probability [#permalink] New post 11 Feb 2004, 12:57
There are 4 identical balls (same size). Each ball could be either RED or WHITE only. What is the probability that there are 2 RED and 2 WHITE balls?
Director
Director
avatar
Joined: 03 Jul 2003
Posts: 656
Followers: 2

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

GMAT Tests User
 [#permalink] New post 11 Feb 2004, 13:17
P(2W&2R) = 3/8
SVP
SVP
User avatar
Joined: 30 Oct 2003
Posts: 1798
Location: NewJersey USA
Followers: 3

Kudos [?]: 29 [0], given: 0

GMAT Tests User
 [#permalink] New post 11 Feb 2004, 13:34
I get 1/4 as the answer.

Each ball can either be RED or WHITE so we have 4 balls hence 2^4 = 16 combinations. Out of these 2W and 2R occur 4 times as follows

WWRR
RRWW
WRWR
RWRW
Hence 4/16 = 1/4
Senior Manager
Senior Manager
avatar
Joined: 11 Nov 2003
Posts: 356
Location: Illinois
Followers: 1

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

GMAT Tests User
 [#permalink] New post 11 Feb 2004, 13:36
anandnk wrote:
I get 1/4 as the answer.

Each ball can either be RED or WHITE so we have 4 balls hence 2^4 = 16 combinations. Out of these 2W and 2R occur 4 times as follows

WWRR
RRWW
WRWR
RWRW
Hence 4/16 = 1/4


Anand,

You missed WRRW and RWWR
SVP
SVP
User avatar
Joined: 30 Oct 2003
Posts: 1798
Location: NewJersey USA
Followers: 3

Kudos [?]: 29 [0], given: 0

GMAT Tests User
 [#permalink] New post 11 Feb 2004, 13:37
Oops my bad. You are right
No of ways you can arrange 2 W and 2R = 4!/(2!*2!) = 6
Total combinations = 16
so P = 6/16 = 3/8
Manager
Manager
avatar
Joined: 28 Jan 2004
Posts: 205
Location: India
Followers: 2

Kudos [?]: 10 [0], given: 4

GMAT Tests User
 [#permalink] New post 12 Feb 2004, 05:14
It is not arrangement ...so there is no difference between WRRW and RWWR!!!!!!!!!!!!!!
Please let me know if my approach is incorrect.

RED BLUE
4 0
3 1
2 2
1 3
0 4

So the probability is 1/5..............
Probability is my weakest...so please pardon me if i did a stupid analysis...and if anyone is posting a reply to my reply the please just copy and send that to me as PM also because tomorrow i will not be able to track this question!!!!! i don't know how to do that if it can be done..and i am sure that is some way of doing that....................
GMAT Instructor
User avatar
Joined: 07 Jul 2003
Posts: 771
Location: New York NY 10024
Schools: Haas, MFE; Anderson, MBA; USC, MSEE
Followers: 9

Kudos [?]: 25 [0], given: 0

GMAT Tests User
 [#permalink] New post 12 Feb 2004, 10:31
mdfrahim wrote:
It is not arrangement ...so there is no difference between WRRW and RWWR!!!!!!!!!!!!!!
Please let me know if my approach is incorrect.

RED BLUE
4 0
3 1
2 2
1 3
0 4

So the probability is 1/5..............
Probability is my weakest...so please pardon me if i did a stupid analysis...and if anyone is posting a reply to my reply the please just copy and send that to me as PM also because tomorrow i will not be able to track this question!!!!! i don't know how to do that if it can be done..and i am sure that is some way of doing that....................


You counted the "outcomes" but they're are not equally likely, hence, you cannot figure out the probability that way.
_________________

Best,

AkamaiBrah
Former Senior Instructor, Manhattan GMAT and VeritasPrep
Vice President, Midtown NYC Investment Bank, Structured Finance IT
MFE, Haas School of Business, UC Berkeley, Class of 2005
MBA, Anderson School of Management, UCLA, Class of 1993

Manager
Manager
avatar
Joined: 28 Jan 2004
Posts: 205
Location: India
Followers: 2

Kudos [?]: 10 [0], given: 4

GMAT Tests User
 [#permalink] New post 13 Feb 2004, 01:10
Well ,Probability = favourable events/total number of events
Sorry to say , i am not yet satisfied......is somebody there to elaborate on this.

Thanks.
  [#permalink] 13 Feb 2004, 01:10
    Similar topics Author Replies Last post
Similar
Topics:
Probability Priti 8 19 Aug 2005, 11:12
Probability mirhaque 9 29 Jun 2005, 18:06
Probability peterpan 4 18 Dec 2004, 19:21
Probability oxon 5 07 Nov 2004, 12:13
Probability.... bdoll_123 0 23 Sep 2004, 07:51
Display posts from previous: Sort by

Probability

  Question banks Downloads My Bookmarks Reviews Important topics  


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®.