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Re: A couple has two children, one of whom is a girl. [#permalink]

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23 Apr 2016, 10:25

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 ? _________________

Thanks and Regards

Abhishek....

PLEASE FOLLOW THE RULES FOR POSTING IN QA AND VA FORUM AND USE SEARCH FUNCTION BEFORE POSTING NEW QUESTIONS

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
_________________

Re: A couple has two children, one of whom is a girl. [#permalink]

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23 Apr 2016, 10:42

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.
_________________

Re: A couple has two children, one of whom is a girl. [#permalink]

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23 Apr 2016, 10:44

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
_________________

Re: A couple has two children, one of whom is a girl. [#permalink]

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08 Sep 2017, 18:36

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

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?

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 )
_________________