Super Duper Extra Hard Brainteaser

jimdmcevoy · #1 03-17-2005, 02:22 PM

I'll open with a well know semi-easy one:

You know that a woman has exactly 2 children. You ask her if she has at least one girl, and she says yes. What's the probability that she has two girls?

Answer in white:

 1/3 

Now, suppose that 1% of all girls are named Sarah, and that if a mother had two girls that the mother would not name both of them Sarah

You know a woman has exactly 2 children, you ask her if she has a girl named Sarah, she says yes.

What are the chances she has two girls?

partygirluk · #2 03-17-2005, 02:39 PM

I'm getting just under 1/5 but I could well be out.

Asufiji2004 · #3 03-17-2005, 02:41 PM

For a 140+ IQ you don't seem too confident.

partygirluk · #4 03-17-2005, 02:41 PM

I am wrong.

__Q__ · #5 03-17-2005, 02:42 PM

i'd say, 1/3

Patrick del Poker Grande · #6 03-17-2005, 02:43 PM

I say 1/3 for both, assuming an equal distribution of boys and girls (that a woman is equally likely to have a boy as a girl, not 60/40 or 55/45 or whatever it is in reality).

jimdmcevoy · #7 03-17-2005, 02:43 PM

[ QUOTE ]
For a 140+ IQ you don't seem too confident.

[/ QUOTE ]

Should a person with 140+ IQ necessarily be confident?

daryn · #8 03-17-2005, 02:44 PM

<blockquote>In risposta di:<hr />
<blockquote>In risposta di:<hr />
For a 140+ IQ you don't seem too confident.

[/ QUOTE ]

Should a person with 140+ IQ necessarily be confident?

[/ QUOTE ]

no

partygirluk · #9 03-17-2005, 02:45 PM

Now I'm getting 199/399, but still not sure. Give me 5 mins.

Asufiji2004 · #10 03-17-2005, 02:48 PM

[ QUOTE ]
[ QUOTE ]
For a 140+ IQ you don't seem too confident.

[/ QUOTE ]

Should a person with 140+ IQ necessarily be confident?

[/ QUOTE ]

in his ability to figure out this xtra hard brain teaser?....yes!!