PG-13

The key is that the host has to eliminate the door without key. Without the host knowingly eliminate that door, the ans would be otherwise.

PG-13

Originally posted by netharmon at 2007-3-15 11:38 PM:
如果真係 2/3 同 1/2 咁大差異, 不如寫個 Program 來 Simulate 10000000 times 睇吓 如果轉的勝出 是近 1/2 定 2/3.

Stimulator... http://www.userpages.de/monty_hall_problem/
OF COZ THERE IS STIMULATOR! its a world known mathmatical problem, and there are of coz more than 1 stimulator on the internet.. search it for more if u think this ones fake

PG-13

Originally posted by playbr2 at 2007-3-15 04:25 PM:
引文一篇[/colo...

The comment is wrong, without another knowingly choose it for u, the probablity will be the same.

first, Player 3 choose 1 ( win, lose, lose),
*before opening the door, the porbably of each door is 1/3 for winning

then, host 2 choose 1 (lose, lose) with the probabilty of 1/3 to pick this set or ( win,  lose) with the probability of 2/3 ,<-- this interferance is critical because the host have to choose the lose door in either situation.

The host' probability of holding a winning door would be 1/2. Because in the cases of (lose, lose) with the probability of 1/3, he has to open the lose door, which left ( lose) door. And in the ( win,  lose) case with the probability of 2/3, the host has to open the lose door, which left ( win).
As a result, with knowingly open ( lose) door, there are only 2 outcomes:
( win)or ( lose). However, because the chance of picking a (lose, lose) is only 1/3, there are 2/3 of chance that the host will have ( win)
So the probability is 2/3
--------------------------------------------------
In case the host DOES NOT knowingly open the ( lose) door
first, Player 3 choose 1 ( win, lose, lose),
*before opening the door, the porbably of each door is 1/3 for winning

then, host 2 choose 1 (lose, lose) or ( win, lose),

Without knowingly open the ( lose) door the host's probability of holding a winning door would be 1/2. Because in case of (lose, lose) with the porbability of having this set is 1/3 and in case of (win, lose) the porbability is 2/3.
So,withouth knowingly pick the set, the chance shall be [1/2x1/3 +1/2x2/3]=1/2
am not expert in stats and i dont think my ans is right anyways

[ Last edited by PG-13 on 2007-3-16 at 02:10 AM ]

PG-13

Originally posted by ming8964 at 2007-3-16 02:39 PM:
整件事只是鬧劇一場, 無謂浪費時間去...

Your additude is kinda.. wrong.... ppl investigate on trivial thing because they want to, but not to show off, even if they want to show off, their discoverary would benefit a lot of ppl.

Why dont you bith on newton since he wonder why the apple would fall down but not goes up.

PG-13

Originally posted by kaichun88 at 2007-3-16 05:26 PM:


The problem has mentioned that ...

Right, but i am saying "AFTER" the host opening the door but "WITHOUT" knowingly which door is the winning door