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

It is currently 04 Aug 2015, 10:38
GMAT Club Tests

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

What is the probability that in a group of 10 students at

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
Senior Manager
Senior Manager
avatar
Joined: 02 Mar 2004
Posts: 328
Location: There
Followers: 1

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

What is the probability that in a group of 10 students at [#permalink] New post 15 May 2004, 15:46
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

What is the probability that in a group of 10 students at least 2 will have the same birthday?
SVP
SVP
User avatar
Joined: 30 Oct 2003
Posts: 1794
Location: NewJersey USA
Followers: 5

Kudos [?]: 47 [0], given: 0

 [#permalink] New post 15 May 2004, 19:19
1- (365C10)/(365^10)

1 - P( that none will have the same birthday.)
Choose 10 different dates for all 10 of them from 365 days in 365C10 ways
Since each birth days can range from 1 to 365 and 10 such people are there total combinations = 365^10

Hi mrihaque

Your P value is > 1

Anand.
Senior Manager
Senior Manager
avatar
Joined: 02 Mar 2004
Posts: 328
Location: There
Followers: 1

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

 [#permalink] New post 17 May 2004, 10:49
Prob of having different birthdays = 1*(364/365)*...*(356/365)

The answer = 1 - the above quantity = 1 - [365P10/365^10]
Intern
Intern
User avatar
Joined: 06 May 2004
Posts: 15
Location: Toronto
Followers: 0

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

 [#permalink] New post 17 May 2004, 12:33
I think anandnk is right as it would be C not P while picking up birthdates
so it would be 1 - (365C10/365^10)
_________________

lets do it together....

Senior Manager
Senior Manager
avatar
Joined: 02 Mar 2004
Posts: 328
Location: There
Followers: 1

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

 [#permalink] New post 17 May 2004, 12:37
well, you are considering only one ordered sequence among 10! possibilities. As the students are different, one need to add the same probability 10! times. Then you'll end up with 360P10/365^10. It does not matter whether one uses C or P, but what matters is basic counting.
  [#permalink] 17 May 2004, 12:37
Display posts from previous: Sort by

What is the probability that in a group of 10 students at

  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®.