["Followup-To:" header set to aus.tv.] * Big LN is quoted & my replies are inline below : > "Mark" <email@example.com> wrote in message > news:firstname.lastname@example.org... >> Can somebody exlpain this one? >> >> (warning, maths question..) >> >> There are some answers on the site, but I still don't get why the >> answer is what it is... >> >> http://www.smart-kit.com/s313/the-best-simple-math-brain-teaser-and-the-controversy-that-surrounded-the-answer/ >> >> Suppose you're on a game show, and you're given a choice of three >> doors. Behind one door is a car; behind the others, goats. You pick a >> door - say, No. 1 - and the host, who knows what's behind the doors, >> opens another door - say, No. 3 - which has a goat. He then says to >> you,"Do you want to pick door No. 2?" Is it to your advantage to >> switch your choice? > > Yes. You'd increase your odds from 1/3 to 2/3. > The best way to imagine it is pretend there are 100 doors. > Your pick is therefore a 1/100 chance. > The host opens 98 other doors where the goats are. > The other door now has a 99/100 chance so you'd switch.
Wrong. You don't know if the door you already picked has goat or car.
In the original 3 door question, you have a 1 in 3 chance of getting it right. Once a door with goat is revealed, your chances increase to 1 in 2, not matter if you change doors or not.
In your 100 door analogy, original odds are 1 in 100 as you say, but with 98 doors revealed, you still only have a 1 in 2 chance.