haydon_peter Posted September 12, 2004 Report Share Posted September 12, 2004 Your on a gameshow. You get to the final, and are presented with 3 doors. Behind one of them, there's a car, while the other two contain goats. Although the show host knows what is behind each door, of course the player does not. After the player makes a first choice, the host opens one of the two other doors, revealing a goat. He then offers the player the option to either stick with the initial choice or switch to the other closed door. Should the player switch? Get your head round this one people. "Tic" Quote Link to comment Share on other sites More sharing options...
MrMonkey Posted September 12, 2004 Report Share Posted September 12, 2004 I think the contestant should punch out the host check the doors and then make his decision :lol: Quote Link to comment Share on other sites More sharing options...
Phatmike Posted September 12, 2004 Report Share Posted September 12, 2004 Surely there's still a 50/50 chance, whether he switches doors or not... Andy, why did you delete your post? :lol:" Quote Link to comment Share on other sites More sharing options...
froggy Posted September 12, 2004 Report Share Posted September 12, 2004 Depends how much you want a goat :lol: Quote Link to comment Share on other sites More sharing options...
tomturd Posted September 12, 2004 Report Share Posted September 12, 2004 Ok then. The car comes with a free goat anyway. :lol: Quote Link to comment Share on other sites More sharing options...
Trials Punk Posted September 12, 2004 Report Share Posted September 12, 2004 Depends how much you want a goat :lol: ← Could do with one of them. i'm getting bored with sheep. Quote Link to comment Share on other sites More sharing options...
-RoBBo- Posted September 12, 2004 Report Share Posted September 12, 2004 Stick :lol: because if he had chose a goat..the presenter would of opened the door with the car behind. :( Quote Link to comment Share on other sites More sharing options...
tomturd Posted September 12, 2004 Report Share Posted September 12, 2004 Stick :lol: because if he had chose a goat..the presenter would of opened the door with the car behind. :( ← No no. Theres 3 doors. 2 goats, 1 car. No matter which door the contestant initially chooses, there will always be a 'spare' goat for the presenter to reveal. Quote Link to comment Share on other sites More sharing options...
-RoBBo- Posted September 12, 2004 Report Share Posted September 12, 2004 No no. Theres 3 doors. 2 goats, 1 car. No matter which door the contestant initially chooses, there will always be a 'spare' goat for the presenter to reveal. ← Oh you just had to piss on my fireworks didn't you. :( But thats jsut my theory, as maybe the presentor would have liked to put the guy out of his misery quicker :lol: Quote Link to comment Share on other sites More sharing options...
Si Posted September 12, 2004 Report Share Posted September 12, 2004 I dont get it :lol: Quote Link to comment Share on other sites More sharing options...
haydon_peter Posted September 12, 2004 Author Report Share Posted September 12, 2004 I think the contestant should punch out the host check the doors and then make his decision :( ← Violance gets you nowhere! If you did that the TV studio's security would bum rape you before you had the chance to open any doors :lol:" "Tic" Quote Link to comment Share on other sites More sharing options...
Dan Campbell Posted September 12, 2004 Report Share Posted September 12, 2004 Its all about the maths, I spoke to tic and I was correct on the theory just a small amount of cheating to find out if my crazy theory was correct, which it was. It seems so obvious. Dan Quote Link to comment Share on other sites More sharing options...
Royaltrials Posted September 12, 2004 Report Share Posted September 12, 2004 The probability that the car is behind one of the doors is a third. When you find out that a goat is behind one of the doors the probability of the car being behind the same door is still one third. The other door now has a two-thirds probability of having a car behind it... So you should switch doors. Thats the answer to the solution (some poncey twatty public school kid asked me this problem when I was at a university interview, saying it's the kinda stuff that they will ask you...) apparantly... although I still think it's 50-50 myself. Quote Link to comment Share on other sites More sharing options...
tank_rider Posted September 12, 2004 Report Share Posted September 12, 2004 The probability that the car is behind one of the doors is a third. When you find out that a goat is behind one of the doors the probability of the car being behind the same door is still one third. The other door now has a two-thirds probability of having a car behind it... So you should switch doors. Thats the answer to the solution (some poncey twatty public school kid asked me this problem when I was at a university interview, saying it's the kinda stuff that they will ask you...) apparantly... although I still think it's 50-50 myself. ← Thats all well and good so long as you look at the problem from a fixed perspective, of the initial choices. If you look at it with a real time, moving perspective, the answer changes to 50/50 and the initial choice becomes superfluous, as the second question may as well be which do you want to choose. If you take for instance the usual scenario of a game show, where this choice occurs, the contestant will change their mind a couple of times before they make their final decision one way or the other, therefore making it a 50/50 decision. Quote Link to comment Share on other sites More sharing options...
dirtbiker Posted September 12, 2004 Report Share Posted September 12, 2004 If you draw a tree diagram you'll find that its not a 50/50 chance. Apparantly some american magazine writer did this in her magazine, had a load of professors and whatnot write in and tell her that she was wrong, and then proved them all wrong. My electronics teacher couldnt remeber the problem properly, so that kinda ruined it for me :P Quote Link to comment Share on other sites More sharing options...
Swindon rider Posted September 12, 2004 Report Share Posted September 12, 2004 moooo Quote Link to comment Share on other sites More sharing options...
excaliborg Posted September 12, 2004 Report Share Posted September 12, 2004 I think that is rubbish, and that: At first, the chance of picking the car is 1/3. once a door has been opened the choices are narrowed to 1/2. no matter what the first chosen door is, the other goat will always be shown, leaving 2 doors, one of which is a car. Therefore I believe it doesn't matter if the contestant switches as the probability is 50/50. Quote Link to comment Share on other sites More sharing options...
Tomm Posted September 12, 2004 Report Share Posted September 12, 2004 I'll try to explain it the way that helped Tic, you have to think hard (Don't reply saying I'm wrong until you have given it at least 10 mins though :( ). If you picked a goat and you change, you get the car. If you picked the car initially, you get the goat. However, because the chance of picking the car initally is 1/3, chances are that you will have picked a goat (2/3), so you should change. So you should swap :P Quote Link to comment Share on other sites More sharing options...
Ingram Posted September 12, 2004 Report Share Posted September 12, 2004 BINGO! I understand it :P i either just had a suden boost of brain power as i am totaly stupid or Tomm should consider a teaching career Quote Link to comment Share on other sites More sharing options...
haydon_peter Posted September 12, 2004 Author Report Share Posted September 12, 2004 I'll try to explain it the way that helped Tic, you have to think hard (Don't reply saying I'm wrong until you have given it at least 10 mins though :( ). If you picked a goat and you change, you get the car. If you picked the car initially, you get the goat. However, because the chance of picking the car initally is 1/3, chances are that you will have picked a goat (2/3), so you should change. So you should swap :P ← The thing you said that helped me was: Chances are, the first time you guess you will be wrong, so changing you mind will help. "Tic" Quote Link to comment Share on other sites More sharing options...
Davetrials Posted September 12, 2004 Report Share Posted September 12, 2004 The MOST i have ever been confused. Quote Link to comment Share on other sites More sharing options...
sexymike Posted September 12, 2004 Report Share Posted September 12, 2004 The MOST i have ever been confused. ← awww bless if u chose a goat first time *bearing in mind the idea of this is to get the car* then you should defo swap, because you could end up with the same, or a car, so why the feck not go for it? Quote Link to comment Share on other sites More sharing options...
Tomm Posted September 12, 2004 Report Share Posted September 12, 2004 awww bless if u chose a goat first time *bearing in mind the idea of this is to get the car* then you should defo swap, because you could end up with the same, or a car, so why the feck not go for it? ← You don't know if you have a goat or not though. The presenter fellow only shows you one of the doors you didn't choose. Time to bring out the embarrassed smiley :P Quote Link to comment Share on other sites More sharing options...
excaliborg Posted September 13, 2004 Report Share Posted September 13, 2004 awww bless if u chose a goat first time *bearing in mind the idea of this is to get the car* then you should defo swap, because you could end up with the same, or a car, so why the feck not go for it? ← I think you've misunderstood! Right i think i've just got it. [] < door 1, your 1st choice. Could be a car if you picked this at first (1/3) [] < door 2, been opened up to reveil a goat. [] < door 3, if you picked a goat (2/3) this is a car as the host wouldnt open up the car door. Understand it now! cheers guys Quote Link to comment Share on other sites More sharing options...
froggy Posted September 13, 2004 Report Share Posted September 13, 2004 (edited) I think you've misunderstood! Right i think i've just got it. [] < door 1, your 1st choice. Could be a car if you picked this at first (1/3) [] < door 2, been opened up to reveil a goat. [] < door 3, if you picked a goat (2/3) this is a car as the host wouldnt open up the car door. Understand it now! cheers guys ← I also think you have googled it too! :P I tried last night lol I found a page with near enough the same answer :P I still don't full understand it though because [] < door 1 REVEILD TO SHOW A GOAT [] < door 2 hidden goat [] < door 3 hidden car No matter which of the 2 remaining doors you choose, door 1 has allready been reveild so this door no longer exists in the competition. You're origional door, when all 3 doors were shut, you're chance of getting a car was 1/3. Now that one door has been reveiled to show a goat youre chance of getting a car is 1/2. After the first door is reveild to show a goat it leavs yiou with 2 remaining options of which 1 being a car and 1 being a goat, how possible can you look at it in X/3? :P Edited September 13, 2004 by Adamm Quote Link to comment Share on other sites More sharing options...
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