From: Eliezer S. Yudkowsky (sentience@pobox.com)
Date: Wed Apr 30 2003 - 10:56:47 MDT
Rafal Smigrodzki wrote:
>
> ### At first I did come up with .5 as the answer, but it seemed too simple,
> and I chose to get confused :-) Thanks for pointing this out.
Yeh... well, you know my remedy for confusion.
> Talking about simple probabilities, here is a problem which initially
> baffled me:
>
> You play a game on TV. There is a large prize behind one of three doors. You
> are given a chance to bet on opening one of them. After you choose, the
> game's moderator will open one of the remaining two doors, an empty one. You
> can now change your bet, choosing the door that has not been opened, or you
> can stick with your initial bet. The question is, what should you do:
>
> a) stick to your previous choice
> b) flip a fair coin and either stick to your choice or choose the one
> remaining door
> c) always choose the one other remaining door
>
> It's really simple.
Here's another trick question that only the true Bayesian will resolve.
You meet a mathematician. "How many children do you have?" you ask.
"Two," he replies, "and at least one of them is a boy." What is the
probability that they are both boys?
I would *not* answer 1/3.
-- Eliezer S. Yudkowsky http://singinst.org/ Research Fellow, Singularity Institute for Artificial Intelligence
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