Two Plus Two Older Archives  

Go Back   Two Plus Two Older Archives > General Gambling > Probability

Reply
 
Thread Tools Display Modes
  #1  
Old 10-06-2002, 04:54 AM
lorinda lorinda is offline
Senior Member
 
Join Date: Sep 2002
Location: England
Posts: 2,478
Default Children

A simpler version of Mike's post, and one I had forgotten until he posted his...
My friend has two children, and I'll tell you that one of them is a boy.
What is the probability that the other one is a boy too?

Reply With Quote
  #2  
Old 10-06-2002, 05:28 AM
BruceZ BruceZ is offline
Senior Member
 
Join Date: Sep 2002
Posts: 1,636
Default Re: Children

1/3
Reply With Quote
  #3  
Old 10-06-2002, 10:41 AM
Mike Haven Mike Haven is offline
Senior Member
 
Join Date: Sep 2002
Location: Northern Ireland
Posts: 2,288
Default Re: Children

i agree with bruce, assuming that the parents don't suffer from prosiarmageddon syndrome of course

the normal possibilities are BG, BB, GB or GG, so if you take out GG because of your friend's statement then there is a one in three chance of the children being BB
Reply With Quote
  #4  
Old 10-06-2002, 11:06 PM
Guest
 
Posts: n/a
Default Re: Children

1/2. The sex of the first child has no bearring on the sex of the second child. They are independent events.
Reply With Quote
  #5  
Old 10-06-2002, 11:14 PM
BruceZ BruceZ is offline
Senior Member
 
Join Date: Sep 2002
Posts: 1,636
Default Re: Children

If she had said that the first one born was a boy, then your answer would be correct.
Reply With Quote
  #6  
Old 10-07-2002, 02:06 AM
Ed Miller Ed Miller is offline
Senior Member
 
Join Date: Sep 2002
Location: Writing \"Small Stakes Hold \'Em\"
Posts: 4,548
Default Re: Children

1/3
Reply With Quote
  #7  
Old 10-08-2002, 04:51 AM
Mason Malmuth Mason Malmuth is offline
Senior Member
 
Join Date: Aug 2002
Location: Nevada
Posts: 1,831
Default Re: Children

There are four possible ways there can be two children. They are:

BB
BG
GB
GG

Notice that the GG case cannot exist since one child must be a boy. This leaves us with only three acceptable cases. Two of those produce girls as the companion. Only BB meets the criterion. So the probability is 1/3. [img]/forums/images/icons/confused.gif[/img]
MM
Reply With Quote
  #8  
Old 10-08-2002, 04:53 AM
Mason Malmuth Mason Malmuth is offline
Senior Member
 
Join Date: Aug 2002
Location: Nevada
Posts: 1,831
Default Re: Children

What a great picture. I bet in real life you don't look that good.

MM
Reply With Quote
  #9  
Old 10-08-2002, 09:09 AM
Mike Haven Mike Haven is offline
Senior Member
 
Join Date: Sep 2002
Location: Northern Ireland
Posts: 2,288
Default Re: Children

[img]/forums/images/icons/blush.gif[/img] you called my bluff

you are very kind, but, actually, i have to admit ...

it's not really me!!

i'm not an art expert by any means, but i think it is called the "mona lisa" - a famous painting of a fifteenth century bathing beauty
Reply With Quote
  #10  
Old 10-08-2002, 07:18 PM
DJA DJA is offline
Senior Member
 
Join Date: Sep 2002
Posts: 209
Default Re: Children

The answer is 0%. No one says, "I have a boy." when they have 2 boys.

[img]/forums/images/icons/grin.gif[/img]

Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 02:16 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, vBulletin Solutions Inc.