Author: Rolf Tueschen
Date: 07:26:50 09/27/02
Go up one level in this thread
On September 27, 2002 at 09:45:47, Uri Blass wrote: >On September 27, 2002 at 08:50:27, Gerrit Reubold wrote: > >>On September 27, 2002 at 08:22:06, Sune Fischer wrote: >> >>>On September 27, 2002 at 08:14:28, Gerrit Reubold wrote: >>> >>>>Hi Sune, >>>> >>>>On September 26, 2002 at 14:47:32, Sune Fischer wrote: >>>> >>>>I disagree, I am sure it doesn't matter whether the host opens a door (with a >>>>goat) KNOWING where the car is or by SHEAR LUCK. The candidate should switch in >>>>either case, thus improving his winning odds from 1/3 to 2/3. Of course, if the >>>>host doesn't know and opens the door with the car (accidently), the game is over >>>>:-) >>> >>>Ok, well at least we agree that if he KNOWS he should switch. >>> >>>So suppose the host doesn't know, and the host opens a door to a goat. >>> >>>What does this tell us? >>>Well, since he didn't know, it means he either had a 50% probability of opening >>>to a goat, or a 100% probability. >>> >>>He gets 100% probability if we are sitting on the car, and he gets 50% if the >>>car is behind the one of the doors he had to choose from. >>> >>>The odds of picking a goat if you have 100% probability is higher than if you >>>only have 50% (obviously), okay? >> >>I don't care what that probability was _before_ he opened the door. The door >>with the goat is _now_ open. > >Suppose for the discussion that the candidate also guess door 1 >and the host always open door 3 in case that door 1 has a goat. > >If I understand correctly you say that the candidate should switch >and get probability of 2/3. > >Do you agree? > >Let assume case i means that the car is behind door i. > >In case 1 the car is behind door 1 so the candidate win only if he does not >switch. >In case 2 the car is behind door 2 so the candidate win only if >he switchs. > >In case 3 the car is behind door 3 so the host expose the car so there >is no game. > >Do you agree? > >The probability for every case is 1/3 before the game start. > >Do you agree? > > >If we know that case 3 does not happen and this is what we know >after the host opened door 3 and found no car Uri, you take all the fun out of it.Because you are proving mathematically my point. But ok, I had made it a while ago. So we two are now in consense? No wonder! Take care, and a beatiful weekend! Rolf Tueschen > then it means >that there are only 2 cases and the probability for every case is >(1/3)/(2/3)=1/2. > >Do you agree? > >It mean that switching is going to give you probability 1/2 > >Do you agree? > >I did not spend some minutes to try to understand >sune's post but I believe that he also understood the point. > >Uri
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.