On Thu, 29 Jan 2009 22:53:28 -0600, Vic Smith
wrote:

Doesn't make sense.
She made her choice when the odds were 2:1 against her.
Since one curtain was eliminated, the odds are now 1:1.
Changing her choice won't change the odds.
The odds changed when the first curtain was opened.
Flip a coin 10 times and it comes up heads each time.
What are the odds of heads on the 11th flip?
Same as they were on the first flip. 1:1.
Or even money for you real gamblers.
Of which Galactic guys don't qualify.
Unless you're wagering quateros on warpsnerk lightbeam racing.

No. You thinking about it the wrong way 'round.

We're talking probabilities. Initially, she had a 1 in 3 chance when
she picked her first door. When Monty revealed the goats behind one
of the doors, her probability of choosing the correct door increased
to 2 in 3.

The key to understanding this is that the past can be ignored when
assessing the probability because it doesn't not matter which door the
player initially picks and which door the host opens. The second key
is that the host knows which door has the car.

It a variation of Bertrand's Box Paradox in which three boxes: a box
containing two gold coins, a box with two silver coins, and a box with
one of each are involved in a similar situation.

Draw out a decision tree - you'll see how it works.

--

If we aren't supposed to eat animals,
why are they made of meat?