Question about the movie "21"?

Question

In the movie "21", Kevin Spacey plays a professor who describes a problem in his classroom. He talks about how a game show host gives a contestant 3 doors to open, 1 with a car behind it. He then describes how the probabilities change if he gives away one of the doors. I didn't really understand the solution...If you have seen the movie can you please explain the problem to me?

Answer 1

i haven't seen the movie but i think i understand what he was talking about

with 3 doors, there is a 1/3 possibility that the door he chooses will have the car behind it

but if he disregards one of the doors, and that door didn't have the car behind it then he has a 1/2 chance of choosing the right one

and a 1 in 2 possibility is better than a 1 in 3 possibility, therefore the probabilities change when he gets rid of a door

Answer 2

Yeah I didn't get the movie either first they playing pokemon cards and then they started to sing Beatles' songs.

I didn't really understand the plot but I liked it so I bought it on dvd and blueray.

Answer 3

first his chances of geting the right one was 99.9% After Spacey showed that it wasnt in 1 of the doors. that took out 33.3% of the chances of getting it right. So u subtract.Making it 66.6% of 2 choices  rounding up to 67% which is an odd numberso when divided by two one value has to be greater thus making the first  answers more likely to be it.

Answer 4

okay well is very complicated and it would take me a while to write out. i know people don't like going through links but i really think that you should go through this one if you want to fully understand it.

http://en.wikipedia.org/wiki/Monty_Hall_...

the problem you're talking about is called the monty hall. wikipedia fully explains it through this link. read through it a few times. it explains the history of it and everything. it is thorough and informative and i understand it now. use the link it helps!!!! hope that helped and best of luck understanding it :)