• Win a car! (or a goat ...)
    56 replies, posted
It better be a good car.
Strange, i've heard this before :rolleyes:
This is old.
It's also seen in the movie 21.
[img]http://i.imgur.com/Zl1S4.gif[/img]
this is dumb
the easier way of explaining it is that the host needs to open the door without the goat that you picked first if you pickd a goat, therefore, if you pick a goat at the beginning and you switch, you always win. since there is a 2/3 chance you pick a goat at the beginning switching has a 2/3 chance of winning
[QUOTE=abcpea;21463594]this is dumb[/QUOTE] You're dumb.
[QUOTE=Vexont;21460542]This is difficult to wrap my head around, but it makes sense if you think about for any length of time.[/QUOTE] I think its hard to wrap your head around anything at all
The first time I read this (like a year ago) I was like, "wut." It makes sense if you take a minute to think about it though. When you FIRST make your choice, the odds that you picked a goat are 2/3. The host then opens a door (he has to open one with a goat). Now, given that it's MORE likely that you picked a goat on your first chance, when he opens the goat door, it's more probable that it was the 'last' door with a goat behind it. Therefore switching benefits you. Of course, if you pick the car on the first go (before you're asked if you'd like to switch) then he can open either door and it wouldn't matter. But you're twice as likely to choose a goat when you make your initial choice, hence swapping is logical.
When I told my friends this they thought I was wrong...
It's easier to understand if there are (example) 1,000,000 doors - 1 car and 999,999 goats. Now the chances of guessing where is the car are 1/1,000,000. Now the host opens 999,998 doors and you are left with two, obviously changing your doors is the logical thing to do (otherwise you're left with 999,999/1,000,000 chances of being wrong)... So it's exactly the same thing here, only with 3 doors instead of 1,000,000.
The possibility is 1 in 3 chance the whole time. But if he opened a door without you chosing anything, then asked you to pick a door, then it would be a 1 in 2 chance. I didn't understand it until he used the same situation with the cards.
[QUOTE=RP.;21464078]It's easier to understand if there are (example) 1,000,000 doors - 1 car and 999,999 goats. Now the chances of guessing where is the car are 1/1,000,000. Now the host opens 999,998 doors and you are left with two, obviously changing your doors is the logical thing to do (otherwise you're left with 999,999/1,000,000 chances of being wrong)... So it's exactly the same thing here, only with 3 doors instead of 1,000,000.[/QUOTE] Winning 999,999 goats is good 'nuff
[QUOTE=werner;21464230]Winning 999,999 goats is good 'nuff[/QUOTE] 999,999 goats would be worth a lot more than a car.
[QUOTE=Adius Shadow;21430170]I would want the goat, I like goat milk. On topic: This is some deja vu right here, I could have sworn reading about the exact same scenario here on Facepunch once.[/QUOTE] I would also want the goat. The gas is cheap, maybe even free, plus it emits milk.
The odds changed to 50/50 when door three was opened. You'd have nothing to gain by switching doors.
[QUOTE=wildwill;21465567]The odds changed to 50/50 when door three was opened. You'd have nothing to gain by switching doors.[/QUOTE] If you had to select a door AFTER the host revealed one of the doors, then the odds would be 50/50. But since you chose a door BEFORE one of the goats is revealed, the odds change completely.
its smarter if you dont switch because the goats back is in door 2 [IMG]http://img714.imageshack.us/img714/1329/12716054743651.jpg[/IMG] see
[QUOTE=werner;21464230]Winning 999,999 goats is good 'nuff[/QUOTE] You don't win 999,999 goats. You win one goat.
[QUOTE=DainBramageStudios;21467215]You don't win 999,999 goats. You win one goat.[/QUOTE] One goat with the power of 999,999 goats?
We did that stuff in school. Several months about statistics and probability
is simple. At the beginning you have a 1/3 chance of picking the car, correct? then he reveals a goat; this actually gives you 33% more chance see pick swap car - goat = 1/3 goat - car = 1/3 goat - car = 1/3 = 2/3 Chance of car or if you don't pick stay car - car - 1/3 goat - goat- 1/3=2/3 chance of GOAT! goat - goat- 1/3 Still it's a win-win situation; either way you still get at least a goat :) For those of you who don't know, it's called variable change.
Isn't this common sense? Surely I'm not the only one who was well aware of this my whole life?
[QUOTE=cyclocius;21431326]I remember this from "The Curious case of the dog in the Night time." Best part of the damn book.[/QUOTE] Same. I'm actually surprised everyone seems to be accepting this, whenever I've seen it before loads of people say it's wrong. My Dad still refuses to believe it.
[QUOTE=Disarray;21430319]I saw this on a TV program on mathematics I think.[/QUOTE] Yeh, something just like this was on this episode of NUMB3RS I watched in school
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