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

It is currently 10 Jul 2014, 07:24

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

A couple has 3 children. Find the probability that atleast

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Manager
Manager
avatar
Joined: 15 Jul 2005
Posts: 106
Followers: 1

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

A couple has 3 children. Find the probability that atleast [#permalink] New post 06 Oct 2005, 21:06
1
This post was
BOOKMARKED
A couple has 3 children. Find the probability that atleast one is a boy. Assume likelyhood of having a boy or a girl is equal and independent.

a) 1/8
b) 1/3
c) 2/7
d) 7/8
e) 5/8

Last edited by chets on 06 Oct 2005, 21:17, edited 1 time in total.
GMAT Club Legend
GMAT Club Legend
User avatar
Joined: 07 Jul 2004
Posts: 5097
Location: Singapore
Followers: 16

Kudos [?]: 130 [0], given: 0

GMAT Tests User
 [#permalink] New post 06 Oct 2005, 21:12
P(Boy) = P(Girl) = 1/2
Events are independent, mutually exclusive.

P(one boy) = P(Boy and Girl and Girl) = 1/2 * 1/2 * 1/2 = 1/8
Manager
Manager
avatar
Joined: 15 Jul 2005
Posts: 106
Followers: 1

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

 [#permalink] New post 06 Oct 2005, 21:17
Sorry, I made a mistake in the question.

It should read, find the probability that atleast 1 is boy.
GMAT Club Legend
GMAT Club Legend
User avatar
Joined: 07 Jul 2004
Posts: 5097
Location: Singapore
Followers: 16

Kudos [?]: 130 [0], given: 0

GMAT Tests User
 [#permalink] New post 06 Oct 2005, 21:24
chets wrote:
Sorry, I made a mistake in the question.

It should read, find the probability that atleast 1 is boy.


Then probability = 1 - P(all girls) = 1 - 1/8 = 7/8

Ans: D
SVP
SVP
User avatar
Joined: 05 Apr 2005
Posts: 1736
Followers: 3

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

GMAT Tests User
Re: Easy Probability [#permalink] New post 06 Oct 2005, 21:48
P(0 boy) = (1/2)^3=1/8
so, P(at least a boy)=total prob-P(0 boy)=1-1/8=7/8

alt: p(a boy)=1/2, p(2 boy)=1/4, p(3 boy)=1/8
so, P(at least a boy) = p(a boy)+p(2 boy)+p(3 boy)=1/2+1/4+1/8= 7/8
Senior Manager
Senior Manager
User avatar
Joined: 14 Apr 2005
Posts: 422
Location: India, Chennai
Followers: 1

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

GMAT Tests User
Re: Easy Probability [#permalink] New post 06 Oct 2005, 21:59
chets wrote:
A couple has 3 children. Find the probability that atleast one is a boy. Assume likelyhood of having a boy or a girl is equal and independent.

a) 1/8
b) 1/3
c) 2/7
d) 7/8
e) 5/8


P(Atleast 1 boy) = 1 - P(All being girls)
= 1 - (1/2*1/2*1/2)
= 1 - 1/8
= 7/8
Senior Manager
Senior Manager
avatar
Joined: 22 Jun 2005
Posts: 364
Location: London
Followers: 1

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

GMAT Tests User
 [#permalink] New post 07 Oct 2005, 01:20
It's D

The probability of not having any boy is
1/2*1/2*1/2=1/8

The probability of having at least one boy:

1-1/8 = 7/8.
  [#permalink] 07 Oct 2005, 01:20
    Similar topics Author Replies Last post
Similar
Topics:
Probability - Couples! DeeptiM 4 10 Aug 2011, 06:19
5 Experts publish their posts in the topic The probability that a family with 6 children has exactly GMATMadeeasy 15 08 Jan 2010, 16:56
Probability--Atleast saurabhmalpani 5 14 Apr 2007, 06:51
A couple wants to have 4 children. The probability of gamjatang 5 24 Nov 2005, 04:24
A couple wants four children. If the probability of having a trickygmat 3 20 Oct 2005, 15:19
Display posts from previous: Sort by

A couple has 3 children. Find the probability that atleast

  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®.