Stay or Switch .... (math-nerds only)

[Debillus]

Monty has a gameshow. Bill is guest on the gameshow.

Monty shows Bill three doors, and says behind one of those doors is a million dollars, the other two are donkeys. You can take home the prize behind the one door you pick.

After Bill chooses a door, Monty says, "We know at least one of the two doors you didn't pick has a donkey behind it, i know where the million dollars is, but instead of showing you that, im going to show you one donkey."

Monty then reveals a donkey behind one of the two doors Bill did not pick and says

"Now that you have seen this Bill, would you like to stay with your first door or switch to the other closed one?"

What should Bill do? Stay, Switch or does it matter?

[Flutterflies]

ummm switch i think

[Gninja]

I would say he has a 50/50 chance of it being a donkey or the money so it really doesn't matter

[Quanth]

uhm ... when he made the first choise he had 33.3 % chance of getting the million.

Now with 1 door gone, he has 50 % chance of making the right choise.

So based on that, ermm it still dosent matter what door he chooses ....



BAH ! i dont like your stopid questions Deb.. go away !

/Q

[Delph]

switch, just map out all the possibilities

Let's say you pick door number 1 and the money is in door number 1
If you switch you lose, if you stay you win
Let's say you pick door number 1 and the money is in door number 2
If you switch you win, if you stay you lose
Let's say you pick door number 1 and the money is in door number 3
If you switch you win, if you stay you lose

So it seems to be a 50/50 possibility but this shows that with switching you'll win twice as much

[Gninja]

Ok I have to say that was extremely nerdy, Delph... but you have a point. I am gonna go with switch as well.

[Flutterflies]

Im going to go with it doesnt matter, cause he was only given one choise and its used up

Wait, i change again. He showed him the donkey behind the door that he picked then he showed him the other donkey, so if he switches he gets the money... i say SWITCH

[Quanth]

The only thing that matters is what Monty says..

After Bill chooses a door, Monty says, "We know at least one of the two doors you didn't pick has a donkey behind it, i know where the million dollars is, but instead of showing you that, im going to show you one donkey."

The answer is in the words, in Monty`s mind he know that Bill chose a donky.

switch Bill ...

[Debillus]

Well ... Some of you gave the right answer, for the wrong reasons but never mind that.
Truth is that you have 1/3 chance of being right on the first door, but you actualy have 2/3 chance of being right on the second. Not 1/2.

So yes. You should definately switch.

The mathematical hysteria of this is all documented here (pdf).

[Delph]

Some of you gave the right answer, for the wrong reasons

I had it right with the right answers, google is a man's best friend

http://www.nerfcoatedworld.com/archives ... y_hall.php

[Debillus]

Disqualified for cheating. Answer was too close to something I read where I got this.

[Flutterflies]

HAHA, been out of school too long. Dont remember all that stuff thanks for making me think

[Kierra]

I think I would take door # 4 that has the pizza the beer and the 6 chip-n-dale dancers in speedos ready to give me a full body massage kthxbye!!!

[Inglorion]

I'll take door #69 with the hot lady behind it......just because

[Balogh]

You should switch.
the change of you choosing the correct door is 1 in 3, the change of not choosing the correct one is 2 in 3.
this means that the change of the million dollars being behind the 2 doors you didnt choose is 2 in 3 aka 66%.
now one of those doors is opened this means they have eliminated one door but this has no implications on the original choice. The change that the price is behind the still closed door and the open door is still 2 in 3, however you know that its not behind the opened door.
this means that the change of the price is behind the not opened door is 66% and the change you choose correctly is only 33%.
Switch is the way to go.

To illustrate this imagine you have to choose out of 1.000.000 doors.
you choose 1 door and the quizmaster then opens 999.998 doors of which you didnt choose.
would you switch then or rely on youre luck of choosing the 1 in a million door?