Jun 18 09:00 PM EDT  10:00 PM EDT Strategies and techniques for approaching featured GMAT topics. Tuesday, June 18th at 9 pm ET Jun 18 10:00 PM PDT  11:00 PM PDT Send along your receipt from another course or book to info@empowergmat.com and EMPOWERgmat will give you 50% off the first month of access OR $50 off the 3 Month Plan Only available to new students Ends: June 18th Jun 19 10:00 PM PDT  11:00 PM PDT Join a FREE 1day workshop and learn how to ace the GMAT while keeping your fulltime job. Limited for the first 99 registrants. Jun 22 07:00 AM PDT  09:00 AM PDT Attend this webinar and master GMAT SC in 10 days by learning how meaning and logic can help you tackle 700+ level SC questions with ease. Jun 23 07:00 AM PDT  09:00 AM PDT Attend this webinar to learn a structured approach to solve 700+ Number Properties question in less than 2 minutes.
Author 
Message 
TAGS:

Hide Tags

Board of Directors
Status: QA & VA Forum Moderator
Joined: 11 Jun 2011
Posts: 4495
Location: India
GPA: 3.5
WE: Business Development (Commercial Banking)

Re: A couple has two children, one of whom is a girl.
[#permalink]
Show Tags
23 Apr 2016, 10:56
HKD1710 wrote: Thanks Abhishek009, I went thru all those solutions and i still did not understand only the following: Quote: WHY do we consider BG, GB as two cases instead of ONE case only. We are not arranging here. I hope its clear with you now, in case of any doubt , please feel free to revert ( Because I know P&C and Prob Concepts are very confusing) !! Happy Preparations Abhishek
_________________



Retired Moderator
Joined: 22 Jun 2014
Posts: 1107
Location: India
Concentration: General Management, Technology
GPA: 2.49
WE: Information Technology (Computer Software)

Re: A couple has two children, one of whom is a girl.
[#permalink]
Show Tags
23 Apr 2016, 11:07
Abhishek009 wrote: HKD1710 wrote: Thanks Abhishek009, I went thru all those solutions and i still did not understand only the following: Quote: WHY do we consider BG, GB as two cases instead of ONE case only. We are not arranging here. I hope its clear with you now, in case of any doubt , please feel free to revert ( Because I know P&C and Prob Concepts are very confusing) !! Happy Preparations AbhishekAny explanation on that specific part i mentioned would bring clarity.
_________________



Board of Directors
Status: QA & VA Forum Moderator
Joined: 11 Jun 2011
Posts: 4495
Location: India
GPA: 3.5
WE: Business Development (Commercial Banking)

Re: A couple has two children, one of whom is a girl.
[#permalink]
Show Tags
23 Apr 2016, 11:25
HKD1710 wrote: WHY do we consider BG, GB as two cases instead of ONE case only. We are not arranging here. BG = Boy takes birth Before Girl GB = Girl takes birth before Boy PS: I know I might be contradicting my own theory of twins , but it is crucial to understand it this way. Even twins born on the same day may be few minutes apart Does it help you anyway ?
_________________



Math Expert
Joined: 02 Aug 2009
Posts: 7757

Re: A couple has two children, one of whom is a girl.
[#permalink]
Show Tags
23 Apr 2016, 11:38
HKD1710 wrote: Any explanation on that specific part i mentioned would bring clarity. Hi, Do not get into kids as B or G,try with another example say there are two different flavours of icecream  V and C.. 50% chances that one can pick either and eat.. we know he ate two and one was surely a V.. what is the probabilty that he had two vanillas, V.. he could have had VC or CV or VV
_________________



Retired Moderator
Joined: 22 Jun 2014
Posts: 1107
Location: India
Concentration: General Management, Technology
GPA: 2.49
WE: Information Technology (Computer Software)

Re: A couple has two children, one of whom is a girl.
[#permalink]
Show Tags
23 Apr 2016, 11:42
Abhishek009 wrote: HKD1710 wrote: WHY do we consider BG, GB as two cases instead of ONE case only. We are not arranging here. BG = Boy takes birth Before Girl GB = Girl takes birth before Boy PS: I know I might be contradicting my own theory of twins , but it is crucial to understand it this way. Even twins born on the same day may be few minutes apart Does it help you anyway ?well neither we need to apply the twin or age or any other theory. lets put it this way: I am told that my neighbour has two child. one is girl another may be boy or girl. I went to my neighbour's house. here are the total case: 1. a boy opens the door (then other child as we already know is girl) hence  BG. 2. a girl opens the door. (then other child could be boy or girl ) hence (GB or GG) This is why we have these three cases. GG is favorable out of three. so 1/3.
_________________



Retired Moderator
Joined: 22 Jun 2014
Posts: 1107
Location: India
Concentration: General Management, Technology
GPA: 2.49
WE: Information Technology (Computer Software)

Re: A couple has two children, one of whom is a girl.
[#permalink]
Show Tags
23 Apr 2016, 11:44
chetan2u wrote: HKD1710 wrote: Any explanation on that specific part i mentioned would bring clarity. Hi, Do not get into kids as B or G,try with another example say there are two different flavours of icecream  V and C.. 50% chances that one can pick either and eat.. we know he ate two and one was surely a V.. what is the probabilty that he had two vanillas, V.. he could have had VC or CV or VV Thanks chetan. Your assistance helps! Kudos
_________________



Manager
Joined: 27 Jun 2015
Posts: 61
WE: Information Technology (Computer Software)

Re: A couple has two children, one of whom is a girl.
[#permalink]
Show Tags
08 Sep 2017, 19:36
TimeTraveller wrote: Sample space = {bb,bg,gb,gg}
Favourable event = {gg}.
Since it's given that one of the child is a girl, the new Sample Space = {bg,gb,gg}.
So, probability = 1/3. Ans (C). Hi Bunuel, If we consider above method, does it mean that the given probability of either boy or girl being 50% is not required to solve the problem? And also can you please tell, the given probability translate into which of the below equations?: P(B U G)= 0.5 or P(B) = P(G)= 0.5 *U = Union



Math Expert
Joined: 02 Sep 2009
Posts: 55668

Re: A couple has two children, one of whom is a girl.
[#permalink]
Show Tags
30 Dec 2017, 01:05
AmoyV wrote: A couple has two children, one of whom is a girl. If the probability of having a girl or a boy is 50%, what is the probability that the couple has two daughters?
A. 1/8 B. 1/4 C. 1/3 D. 1/2 E. 2/3 VERITAS PREP OFFICIAL SOLUTION:While every bone in your body wants to say 1/2, that is not correct! This is tricky conditional probability and considering the different possibilities is the best way to get it correct. If the couple has 2 children then there are 4 possibilities: BB, BG, GB, GG. If one of the children is a girl then only 3 possibilities remain: BG, GB, GG. Of those 3, only one is favorable to create 2 daughters (GG) so the answer is 1/3. Answer is (C )
_________________



Manager
Joined: 05 Dec 2016
Posts: 111

Re: A couple has two children, one of whom is a girl.
[#permalink]
Show Tags
12 May 2018, 04:59
OFFICIAL SOLUTION Solution: While every bone in your body wants to say 1/2, that is not correct! This is tricky conditional probability and considering the different possibilities is the best way to get it correct. If the couple has 2 children then there are 4 possibilities: BB, BG, GB, GG. If one of the children is a girl then only 3 possibilities remain: BG, GB, GG. Of those 3, only one is favorable to create 2 daughters (GG) so the answer is 1/3. Answer is (C )
_________________
lets all unite to reach our target together



Manager
Joined: 14 Jul 2014
Posts: 90
Location: India
Concentration: Social Entrepreneurship, Strategy
WE: Information Technology (Computer Software)

Re: A couple has two children, one of whom is a girl.
[#permalink]
Show Tags
21 Sep 2018, 04:47
REDWASP2205 wrote: chetan2u But knowing One of them is a girl, shouldn't we remove BG from the possible cases. As the order isn't given here, we can't remove BG form the same set. All we may remove is BB, Boy and a Boy as this is an irrelevant answer option for us here. As we already know that one of the Child is girl.



Intern
Joined: 30 Dec 2014
Posts: 1
GMAT Date: 03142015

Re: A couple has two children, one of whom is a girl.
[#permalink]
Show Tags
21 Sep 2018, 05:52
Bunuel  Need your help to shine some more light on this, if possible. (I know this post is very old) How can we use the probability approach in this question? I understand that one of the children is already a girl. The probability that the other child is a girl is 1/2. How does that line of reasoning completely fail here? Thanks in advance. I am trying to understand the probability approach better here but am failing.




Re: A couple has two children, one of whom is a girl.
[#permalink]
21 Sep 2018, 05:52



Go to page
Previous
1 2
[ 31 posts ]



