[mark]

Here's something to occupy your mind...

You're on a gameshow. In front of you are three doors. Behind one door is a car, behind the other two are goats. You get to choose a door and keep whatever is behind the door you choose. (N.B. You want the car, not a goat!) You choose a door, then the gameshow host opens one of the other doors to reveal a goat. You may now switch your choice of door. Should you switch?

[dave]

before he opened the door you had a 1 in 3 chance of getting the car. Now you have a 1 in 2 chance. You should swap.

[underground]

WTF!? But one of the other doors might have a goat behind too! You could spend ages worrying and not know which door to go for then, but if he hadn't opened it then why would you have even thought about switching?

I'd say stick with the door- I reckon having to make a choice like that would give me a nervous breakdown or at least a coniption!

[Bubba]

But haven't you got a 1 in 2 chance if you stay with the one you've got?

I kinda like goats, being a country boy.

[underground]

Bet you've bummed a few, you dirty old goat  :D

[dave]

I can assure you that mathematically you should swap - its a well known probability problem.

Think about it logically. At first theres a 2/3 chance you'll have originally picked a goat. He shows you the other goat, thus you're now on a 2/3 chance that you know here both goats are, and thus a 2/3 chance you've got the car if you swap.

Consider if you dont swap. You're chances of getting the car are back down to 1/3, the odds of picking 1 from the original 3.

[Bubba]

Bet you've bummed a few, you dirty old goat  :D

They generally offer a much wilder ride than a sheep.

Nothing compares to an angry badger though.

[Bubba]

I can assure you that mathematically you should swap - its a well known probability problem.

I can see your maths but I just don't like it, no sirree!

Just as well I like goats really.

[mark]

thus you're now on a 2/3 chance that you know here both goats are

Not quite. You don't get to see what's behind the door you initially choose, so you only know the location of one of the goats - the one the host shows you after your initial choice.

[dave]

Not quite. You don't get to see what's behind the door you initially choose, so you only know the location of one of the goats - the one the host shows you after your initial choice.

thats what i mean, you know where one is for sure, and theres a 2/3 chance you've picked the other one, thus theres a 2/3 chance you know where both are (the other 1/3 is the eventuality that you picked the car initially) adn thus a 2/3 chance that when you change you're on the car.

If anyone don't belive me, give a workmate 3 upturned coffee mugs, a blob of blu-tack to represent the car, turn away and get them to do it with you, making sure they know which ones the empty ones are.

[mark]

Yup, you're spot on.

Much better than doing it with blu-tak, do it with a pound coin / tenner / as much as they're prepared to put up. Get them to hide it under one of the three mugs and you then choose. Obviously if you don't find the cash you pay them the equivalent amount but they should be happy if they think you only have a 1 in 3 chance of getting their money. Should pay for a few drinks!

[dave]

Or another way to consider it:

You pick your first pick.

Whats the chance you're on the car? Theres a 1/3 chance you're on the car, and a 2/3 chance you're not on the car.

The guy shows you a goat and effectively takes that box out of the running.

Theres still a 1/3 chance you're on the car (as when you originally picked), and a 2/3 chance you're not, thus odds-on you're not on the car, so swap!.

[underground]

I'd like to know the odds on there actually being a gameshow on the box where the contestants could win a goat! What if they live in a flat...

Actually dave, don't I recognise you from your avatar? You look like you should know your stuff when it comes to gameshows  

[dave]

Your moneys safe, but are you going to keep your prizes, or gamble for a speedboat/caravan. You've got the time it takes the board to revolve to decide.

Non-dart player to throw first.

[underground]

Jeez, I used to effin' love Bullseye! Just before bathtime on a Sunday...

[Bubba]

You mean your weekly wash.

[dave]

"out of the black and into the red, nothing in this game for two in a bed".

[underground]

I remeber getting my first bone on that I was embarassed of after that- watching 'Tales of the unexpected', some couple gettin' jiggy, and out it pops through my pyjamas!

I'm feeling all nostalgic now

[Avoiding the Traitor]

Bubba - Look at this this sexy 'un!! a perfect one for you to bum!

[underground]

Just don't ask it for a gam

[Bubba]

Here's my good ole' boys just gittin her ready!