Comments by "Kim O\x27Brien" (@kimobrien.) on "The Simple Question that Stumped Everyone Except Marilyn vos Savant" video.

The host could open the door randomly and reveal the prize but obviously unless the host said he would play for the contestant than it wouldn't be a win for the contestant.
1
@Stubbari The host doesn't have to know which door has the car because if he opens the door with the car the contestant loses.
1
@max5250 No the host only needs to open a door. If the prize is behind the door the host opens the rules of the game can make the contestant a winner or loser. If the host opens the door with a goat then the contestant knows that his first decision gave him one in three odds of winning and now he has a one in two chance of winning if he makes a new decision. Since he already tried door one and lost and the game does not reshuffle the prizes he would have a better chance at winning by picking the other door. It's not what the host knows that is important but the fact that the game does not reshuffle the prizes and the door opening if the prize was initially behind it on the first round. It actually depends on the rules of the game and how the host imparts the information.
1
@max5250 Okay so Monty Hall always knows the answer and never opens the door with the car? Does he also always play the game the same way? Does he ever let the contestant win on the first round or does he always go to a second round? We assume he doesn't reshuffle the car. If you can't win on the first round than why would that decision affect the second?
1
@max5250 So you agree that the first round and the goat revelation has no effect on the chances of winning in the second round and therefore it makes no difference which door you pick in the second round. Which just the opposite of what she said. Her statement of switching doors only makes sense if you can sometimes win in a one round game.
1
@max5250 But if the player had zero chance of winning on the first round so only her second choice matters and she has just a 50% chance of winning no matter what door she picks if she can't win on the first round choice. The odds she picked the correct door on the first round are 33% but since she can't win on the first round only the choice made in the second round matters. Where picking either door left gives odds of 50/50. Her odds of wining improved when Monty Hall opened the door with the goat not when she made a second choice. She must make a second choice but it has nothing to do with the first since she couldn't win the first time around.
1
@max5250 No Let's make a diagram with 3 doors ABC i'll put the car behind door C since the game is symmetrical it makes no difference which door I put it behind. So I start with ABC ABC ABC ABC for Doors. I pick a door symbolized by lower case. aBC AbC ABc now Monte Hall removes a goat (bad door). aC bC Ac or Bc now if don't change I have won 50% of the tme. Ac Bc aC or bC now if I do change I have won 50 % of the time. So unless Monte Hall is limited in which goat he can remove I don't see how you odds improve beyond 50/50. Is there any reason to believe door C is any better than door A or B? Or is it only better because I told you the car was behind it to begin with?
1
@max5250 Okay i finally see where my mistake is. Even though he could create 12 situations he never creates more than 9 as far as the player is concerned.
1