GMAT Question of the Day - Daily to your Mailbox; hard ones only

It is currently 17 Jul 2018, 16:04

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.

Close

Request Expert Reply

Confirm Cancel

How many randomly assembled people do u need to have a

  post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
Manager
Manager
avatar
Joined: 16 Oct 2008
Posts: 54
How many randomly assembled people do u need to have a [#permalink]

Show Tags

New post 28 Oct 2008, 05:50
3.How many randomly assembled people do u need to have a better than 50% prob. that at least 1 of them was born in a leap year?

--== Message from GMAT Club Team ==--

This is not a quality discussion. It has been retired.

If you would like to discuss this question please re-post it in the respective forum. Thank you!

To review the GMAT Club's Forums Posting Guidelines, please follow these links: Quantitative | Verbal Please note - we may remove posts that do not follow our posting guidelines. Thank you.
Director
Director
avatar
Joined: 14 Aug 2007
Posts: 695
Re: Please help # 2/4 [#permalink]

Show Tags

New post 28 Oct 2008, 07:01
Natasha0123 wrote:
3.How many randomly assembled people do u need to have a better than 50% prob. that at least 1 of them was born in a leap year?


Heck, this took a long time..I don't think this question will appear in GMAT though.
Can you also please provide options when you post questions?

Leap year occurs once every 4 years, so probability of any random person to be born in leap year is 1/4.
I think minimum 3 people will be needed, but am not sure unless options are provided.
Manager
Manager
avatar
Joined: 16 Oct 2008
Posts: 54
Re: Please help # 2/4 [#permalink]

Show Tags

New post 28 Oct 2008, 07:04
Thanks a lot :) Really, but there's no option provide..

Here' the solution, really confuse

Prob. of a randomly selected person to have NOT been born in a leap yr = 3/4
Take 2 people, probability that none of them was born in a leap = 3/4*3/4 = 9/16. The probability at least one born in leap = 1- 9/16 = 7/16 < 0.5
Take 3 people, probability that none born in leap year = 3/4*3/4*3/4 = 27/64.
The probability that at least one born = 1 - 27/64 = 37/64 > 0.5

Thus min 3 people are needed.
VP
VP
User avatar
Joined: 05 Jul 2008
Posts: 1333
Re: Please help # 2/4 [#permalink]

Show Tags

New post 28 Oct 2008, 13:01
Natasha0123 wrote:
Thanks a lot :) Really, but there's no option provide..

Here' the solution, really confuse

Prob. of a randomly selected person to have NOT been born in a leap yr = 3/4
Take 2 people, probability that none of them was born in a leap = 3/4*3/4 = 9/16. The probability at least one born in leap = 1- 9/16 = 7/16 0.5

Thus min 3 people are needed.


The problem makes an assumption that all people are born in the same century??? I was stuck on that for a while.

--== Message from GMAT Club Team ==--

This is not a quality discussion. It has been retired.

If you would like to discuss this question please re-post it in the respective forum. Thank you!

To review the GMAT Club's Forums Posting Guidelines, please follow these links: Quantitative | Verbal Please note - we may remove posts that do not follow our posting guidelines. Thank you.
Re: Please help # 2/4   [#permalink] 28 Oct 2008, 13:01
Display posts from previous: Sort by

How many randomly assembled people do u need to have a

  post reply Question banks Downloads My Bookmarks Reviews Important topics  

Moderator: chetan2u

Events & Promotions

PREV
NEXT


GMAT Club MBA Forum Home| About| Terms and Conditions and Privacy Policy| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

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®.