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Topic: Maths question
Replies: 354   Last Post: May 31, 2007 8:04 PM

 Messages: [ Previous | Next ]
 Troy Piggins Posts: 3 Registered: 5/25/07
Re: Maths question
Posted: May 25, 2007 12:39 AM

* Big LN is quoted & my replies are inline below :
> "Mark" <buggy@earwax.com> wrote in message
> news:1nmc531b52dpuv1nctlupp6on3969h2l9k@4ax.com...

>> 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...
>>
>>
>> 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

>
> 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.

--
Troy Piggins

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