Reply to: Maths question II

[CheeseSlice]

Mr C has just explained it to me using 100 doors. It IS much clearer that way.

I disagree. The number of doors is irrelevant to me. The only thing that 'solved' this for me was understanding that Monty must know where the car is, and he must play properly (i.e. never opening the door with a car) to ensure the player gets the decision to switch or not.

If Monty doesn't know, and just plays a random game, even after opening 98 of the 100 doors without revealing the car, then you may as well keep your original choice. All he would have done is increase your chances from 1/100 to 1/2.

[cojak]

Here it is explained.

Understanding the Monty Hall Problem | BetterExplained

Yes the key is Monty is opening a door where he knows the car isn't. Therefore the other door is more likely to have the car behind it.

If there were a hundred doors, you pick one and then he opens the other 98 then the chances are almost certain that the car is behind the other door. With three doors it isn't as clear.

Mr C has just explained it to me using 100 doors. It IS much clearer that way.

[BlasterBates]

Here it is explained.

Understanding the Monty Hall Problem | BetterExplained

The point is if Monty doesn't know where the car was he would sometimes open a door where the car is. Therefore overall it would be a 50/50, presuming that you made a choice without knowing what was behind the door which Monty opened, and that sometimes he opened a door with the car behind. In the cases where he opens a door and there isn't a car and you know there isn't a car, you have a higher probability of finding the car behind the other door.

If there were a hundred doors, you pick one and then he opens the other 98 then the chances are almost certain that the car is behind the other door, because the door you selected only had a 1/100 chance of having the car, whereas the other door has a 99/100 chance. With three doors it isn't as clear.

[vetran]

What is with these one line negative comments?

Don't like a post? Close it. Why waste time commenting?

because they are sad.

[Churchill]

What is with these one line negative comments?

Don't like a post? Close it. Why waste time commenting?

Have a ,

[CheeseSlice]

When you make your guess, one of the other two doors is opened. If there is a car, you lose.

This bit intends to mislead. It suggests a random game.

If the game is played where the first door opened can be a car, then it doesn't matter if you switch or not. Its 50/50.

However, if the game is played so that the first door opened by Monty is never a car (because he knows where it is), then you get a 2/3rd's chance of winning by switching choice.

2/3rds of the time you initially picked wrong and Monty has to hide the door with the car. And during that 2/3rds he always eliminates the door with no car for you.

Do I win a prize?

[eek]

Bellend.

You shouldn't talk about yourself like that

[suityou01]

Twunt

Bellend.

[MarillionFan]

What is with these one line negative comments?

Don't like a post? Close it. Why waste time commenting?

Twunt

[xoggoth]

What is with these one line negative comments?

Don't like a post? Close it. Why waste time commenting?

[EternalOptimist]

Tedious twat.

Yep, but you are not the only one. I am as well

[xoggoth]

Nope, had some vodka and it still makes no sense.

Suppose there are two prizes behind different doors, a car and a motorbike, and two contestants, independently and unknown to each other, choose 1 and 3 opens empty. Contestant 1 wants a car so he improves his chances by switching to 2, but contestant 2, who wants a motorbike, also improves his chances by switching to 2?

This is total, utter bollox!

[xoggoth]

Seen this Monte Hall thing before and I still don't understand it. How is having two possible doors after a third has been opened different to there only ever having been two doors in the first place? Can some genius explain it?

PS I need a vodka. It will all be clear then.

[ASB]

Switching improves from 1/3 to 2/3.

Monty hall problem.

[MarillionFan]

Imagine you are on a game show.
There is a prize car behind one of three doors, and you get to guess which one.


When you make your guess, one of the other two doors is opened. If there is a car, you lose.
If not, you can stick with your original guess, or switch to the other closed door.

you guess door 1. One of the other doors is opened, door 3 - no car.
which of the two closed doors do you pick door 1, or door 2?

a) is it better to stick with 1
b)is it better to switch to the other closed door, 2
c)it doesn't matter . either 1 or 2

Tedious twat.