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?

Re: Children
 

1/3

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

Re: Children
 

1/2. The sex of the first child has no bearring on the sex of the second child. They are independent events.

Re: Children
 

If she had said that the first one born was a boy, then your answer would be correct.

Re: Children
 

1/3

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

Re: Children
 

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

MM

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

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]