Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

Re: The "two child problem"



I was given an equivalent problem in my Math 8 class at Cal:

You are playing bridge. An opponent accidentally exposes one
of the cards dealt him. You see it, and you have not yet seen
your own hand. All you are sure of is that the card you saw
was an ace, nothing more. What is the probability that your
opponent has at least one more ace in his hand?

Suppose that you could tell that his ace was red. What is
the probability that he has at least one more ace?

Suppose that you could tell that his ace was of hearts. What
is the probability that he has at least one more ace?

In the way I have phrased the problem one will conclude that
the answers to these three hypothetical situations differ.

It turns out that philosophy is more difficult than physics.
That's why it is a good idea to keep language very simple in
physics - so it shouldn't become philosophy!

Leigh