# Marilyn and the goats

Nicola, it does matter. The mistake that we were making before was ignoring the fact that one door has already been discounted. When this happens, if you ‘start again’ then yes, the probabilities are 50:50. However, if you continue to take this opened door into consideration - the mathematically correct way of doing it - the maths turns out to be a conditional probability and the probabilities change to 33:67.

Have a look at the site Ben linked to, and you’ll see why in some detail.

Ben, Rich, etc - I don’t doubt that you’re right, and well done for all being a bit genius. But for the sake of argument I’m going to say that the problem refers to a “real-life” situation and I think in the majority of cases, a person in real life who was in that situation would say “righto - that third door’s out of the buggering way, it’s a 50/50 chance, I’ll just give it a random guess”. So the “conditional probability” can go on a nice journey up my rear end … oh I give up.

I may sound rather irate here. But trust me, I have serious issues with this problem. Ask Ben- I almost mauled him in Pizza Express when he tried to explain it to me again

PS… a goat bit me once. little fucker. I am consoled by the fact that the french / japanese or someone probably eat them (generalisations ahoy)

i have a simpler solution for the contestant of this frightfully dull and pointless game show.

Get a life, and BUY yourself a car

moron

i would definitely grab teh goat and run. but im a bit kinky like that.

well at least now I know for when I’m in that situation.

But I really don’t understand on how changing you mind will help. For all you know you got it right the first damn time.

i think everyone’s missing the point; who the hell is marilyn? is she the goat, the contestant, the host or the car?

Good question Louise!! To wit the answer is:

None of them! Marilyn vos Savant is an American newspaper columnist who deals with mathematical and logical puzzles, as well as more traditional self-help advice.

She was the person who said that the probability would NOT be 50:50 and lots of mathematicians wrote in saying “You are wrong. Women can’t do maths” and after a long debate they finally conceded it to her. The story may have been axaggerated a little but that’s who she is at least.

wikipedia.lotsofinformation.com/ … ll_problem

Yarrrr

• ben

it doesn’t matter what door she picks after the host opens the third one with the goat.

you might think the probability for switching becomes 2/3 from 1/3…
but, after the third door is opened its not out of 3 anymore.
its a new game.

so 1/2 either door.