/sci/ - Science & Math

>>1020378
The Monty Hall problem states that if OP is such a faggot why does he continue to come on here and exploit such faggotry instead of fucking off?

>>1020384

OP, you are A faggot.

4 out of 5 doctors agree: OP is a giant faggot.

3 doors, you get to choose one

2 have a goat behind them, 1 has a car (you want the car)

after you choose a door, the gameshow host (monty hall) opens a door with a goat behind it.

he then asks you if you want to keep what's behind your door, or pick the other one.

The questionk is, is it in your best interest to switch, or should you stay? Or does it not matter?

I won't give you the answer, but it's easy to find.

it doesnt matter if you switch or not. its 50/50 either way

>>1020396
The answer is yes, it's in your advantage to switch.

>>1020396
So, the question is, there are two doors, and you have to pick one? 50/50 chance, obviously.

>>1020404
no
1/3 chance the door you first picked is right
1/2 chance the other one is right

When you originally chose, your odds were 1 in 3.

When he's asking you to choose a new door, your odds are now 1 in 2.

Choose the new door.

>>1020422
>>1020423
the first door doesnt matter because its a new situation. 1/2 chance for one door means the other door has to be the other 1/2. 50/50

>>1020423
THIS MAN IS CORRECT. PLEASE STOP BEING FAGGOTS AND /THREAD.

its only in your favour to switch if you know that the show host knows where the car is. In an example such a deal or no deal, where the banker doesnt know where the big money is, then the probability remains 50/50.

There are many answers, but as much detail as they go into, most of them are wrong. They keep making the erroneous assumption that your first choice mattered (it doesn't, the host always reveals a goat and leaves you with two doors), and that the decision to "switch" between the two remaining doors is any different than just picking one with a 50/50 probability.

>>1020438
>>1020423
>>1020422
who said the door he opened was your door?

>>1020449
No

>>1020443
That picture assumes that you picked the wrong door initially. Fail.

The thing i never got, with the second door.. You have to choose to stay or switch, which is 50/50 either way, because your not just choosing to switch, your choosing to stay?

>>1020438
no because you eliminated a choice when you picked a door

look at it this way:
there is a 1/3 chance you pick right the first time
so he can open either wrong door with equal probability
in the 2/3 chances you pick wrong he will have to pick the other wrong door to open
thus you have eliminated that chance and the remaining door is right 1/2 times

switching gets the winning door 2/3 of the time dumbasses, think it through

and fuck you trolls

>>1020480
And the other door is right 1/2 times tho?

Three doors. Door G1 (goat1), G2 (goat2), and C (car)

You pick door G1:
He opens door G2
You switch to door C
Result, win.

You pick door G2:
He opens door G1
You switch to door C
Result, win

You pick door C
He opens either door g1 or g2
you switch to the other goat door
Result, lose.

Now lets do you not switching:

You pick door G1:
He opens door G2
You do not switch.
Result, lose.

You pick door G2:
He opens door G1
You do not switch
Result, lose

You pick door C
He opens either door g1 or g2
do not switch
Result, win.

If you switch you have a 2 in 3 chance of winning, if you do not switch you have a 1 in 3 chance of winning.

>>1020480

But the door you've already picked, at that point, also has a 1/2 chance to be the right one.

>>1020500
Doors don't "gather" probabilities based on past actions. They are static.You fail at math.

>>1020512
you troaling?

>>1020512
0/10
typical trollfag trying to cause a shitstorm

>>1020512
probabilities update with new information about situations, faggot. lrn2bayes

http://en.wikipedia.org/wiki/Bayes'_theorem

It has probably been said but.

Everytime you pick a goat-door and change, you win. 2/3.
Everytime you pick a win-door and change, you lose. 1/3.

Everytime you pick a goat-door and don't change, you lose. 2/3 to LOSE.
Everytime you pick a win-door and don't change, you win. 1/3 to win.

>>1020512
You need to be more subtle.

I choose a door, then Hall open a different door, revealing a goat. However, instead of me then being given a chance to switch, I am escorted out of the room, and a different person who has not witnessed these events is brought in. He is then given the choice of picking between the doors, hoping to pick the one with the car. What are his chances of success?

>>1020544
50%, of course.

>>1020544
He loses the advantage of knowing the door you have chosen. 1/2

>>1020549
>>1020560
So, if he picks the door I had originally chosen, he would have a 1/2 chance of getting a car, but if I had stuck with it, it would have been a 1/3 chance? Is it in a state of superposition, with the chance being based on magical brain waves?

>>1020580
No, if he picks the door you initially chose, he has a 1/3 chance of winning the car.

If he picks the door you didn't choose, he has a 2/3 chance.

He doesn't have the above info. All he knows is that the sum total here is 1/1 chance, but divided between two doors. 50%

>>1020544
2/3 chance you picked a goat. So 2/3 chance he shows you the other goat (like hell he's going to show the car). 1/3 chance you picked the car, and switching will end in you losing.
So 2/3 chance to win if you switch.

>>1020685
So, it's both possible probability sets at once?

You just went full retard.

>So 2/3 chance to win if you switch.

No, 1/2

>>1020705
The host has to open a door.

He can not open the car door
He can not open the door that you have picked.

If you picked a goat door he must open the other goat door, meaning switching makes you win.

If you picked a car door he can open either goat door, switching makes you lose.

If you pick a goat door initially (2/3 chance of picking a goat door), switching always forces you to pick the car door, because the host HAS to open the other goat door.

The only way switching makes you lose is if you initially picked the car door (1/3 chance)

>>1020725
and if you have a 1/3 chance of losing, you obviously have a 2/3 chance of winning.

Holy shit. How the fuck does going from 3 doors to 2 change the probability of 1 being the right one out of 2?

It's a 50% chance that you have the correct door once he reveals the goat. All this fucking 2/3 shit is absolutely useless, seeing as there are 2 remaining doors and you have 1 chosen.

>>1020705
The original player and the replacement player have different information.

This gives the original player an advantage.

Here's a more obvious example:
There are two doors.
The host tells the player, the car is behind the left door.
Now, the original player is removed, and an ignorant player is brought in and not told anything.
What are his chances of choosing the correct door?
Hint: It's not 1.

>>1020725
>>1020734

You're missing the poster's new premise. Seen here:
>>1020544

>>1020742
Get a deck of cards. Pick one card to be the car

and two cards to be the goats


Pick a random card. Since you know you are going to switch throw that card out. If it was the car card then you lose.

If it was a goat card look at the two remaining cards. One is a goat, the other is a car.

Throw the goat card out since thats the door he opened.

you win.

The only way to lose if you always switch is if you picked the car the first time.

thats a 1/3 chance.

1/3 chance of losing = 2/3 chance of winning.

>>1020770
but thats obviously 50/50 is anyone even discussing that?

>>1020512
That's specifically why this problem works. The probability that your initial choice was right is 1/3. The probability one that was not your initial choice was right is 2/3. The chance you were right stays at 1/3, and the chance one this isn't the one you chose stays at 2/3.

>>1020784
The person you keep responding to is.

>>1020500
>>1020500
>>1020500
>>1020500
>>1020500
>>1020500
>>1020500
>>1020500
>>1020500
>>1020500
>>1020500
>>1020500

These are the only possible scenarios. If you can't get the answer from this, google it. If you can't understand it from that, you are a faggot. I am sorry.

It is in your favor to switch doors. End of discussion.

>>1020770
The post you are referencing is 100% irrelevant.

>>1020798
not that i can see.

>>1020742
You guys are absolutely huge fags.

Imagine that it was 1 million doors that you started with instead of 3. You pick one and the host gets rid of every other door except one. Is it more likely that you picked the door on your first try (1/1,000,000) or that the door he did not eliminate was the right one?

>>1020805
>I am automatically right because I posted an image macro

>>1020480
Don't get pissed because you don't know the answer, look at this post and read it. This is right, and you can troll others whenever you realize it it the right one.

>>1020725
Here's your post.
I know it's yours, as you stick yer name on everything.
Backtrack from there.

Let's say you are trying to guess someone's name. You guess the person's name is James Michaels. He says "It's either that or William Cox." What do you think his name is?

>>1020808
No, it's not.

It's actually a sensible question, given the scenario.

>>1020853
That example is 100% irrelevant.

>>1020877
no it isn't you 12 year old troll

>>1020864
No, it's completely unrelated.

I take a six-chamber revolver and put a single bullet in it, spin the chamber and pull the trigger 5 times, none of those times resulting in the gun firing. You walk in the room, unaware of the events which transpired, put the gun to your head and pull the trigger. What is the probability that you will die from this Russian roulette encounter? Hint: it's not 1/6.

>>1020849
thats a homer simpson image macro

its implying that a door is both 50% and 33% likely to have the goat.

I am explaining why this is not the case, by trying again to get people to intuitively 'get' the problem

its not working because everyone is a moron. I thought it was 50/50 at first also but a few minutes of thinking allowed me to see why this is not the case.

its not 'both at once' because the doors themselves don't have any probability, its the choice that has probability. The doors themselves, the car door has a 100% chance of being the car door, the goat doors have a 0% chance of being the goat door.

the probability comes from the picking between them.

Because the first contestant had information about the doors that the second does not, he has a greater chance of picking the correct door.

OP here. What the hell is wrong with you, /sci/. What the hell.

>>1020913
>I thought it was 50/50 at first also but a few minutes of thinking allowed me to delude myself

>>1020903
>LOL IF I FLIP A COIN AND I KNOW IT'S GOING TO LAND ON HEADS ITS NOT 50% ANYMORE !!!!!!!!!
It is 1/6 to the person about to pull the trigger because he doesn't know any better, you retard.

That's the whole point of probability.

its 50/50

either you win the car or you dont

>>1020947
it's 100%

either you are a retard or you are

>>1020877
There is a finite number of names in the world. An injective function could be easily devised which maps each name to a number (i.e. every name gets a number, each number gets at most one name). So each name represents a door. The likelihood of guessing someone's name without prior information is pretty much zero. Therefore, the alternative name that is give is likely the right one, just like the doors.

>>1020933

Probability isn't altered by ignorance. The fact that the new person thinks it's 1/6 doesn't make it actually 1/6.

>>1020932
THE ONLY WAY TO LOSE IS IF YOU PICK THE CAR THE FIRST TIME WHY IS THAT SO HARD TO UNDERSTAND?

>>1020954
It actually is

If you have no idea that the gun has been shot 5 times already, the probability for you the next shot will kill is 1/6, but if you are aware of the previous 5 blank shots, the probability that the next shot will kill you is 1/1.