1/7000000000000 or 50/50

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Caravelle

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torno said:
WanderingFool said:
The way you see it, there is a 50/50 chance, which is right, in a sense.

But the odds of your friend dying are actually the 1 to 7 billion. To you, its a 50/50
That's how I see it. Scientifically (or mathematically, whatever) the odds are 1/6999999999 because of the number of people. Philisophically, it's 50/50 because it's either him, or not.
"Philosophically", okay. (or "mentally").
Care to explain to us how Philosophical Probability Theory works ?

The human brain's inability to grasp probabilities isn't in itself a rule of probabilities.

Dr Druza said:
However, the question of whether you use 50/50 or 1/7 BIL is a matter of how you phrase the question:
Chances of friend dying vs anyone else: 50/50
Chances of friend dying vs someone else: 1/7 BIL
Someone being one person, anyone being the collective 7 BIL people represented as one "person" (anyone).
I think that makes sense...
It makes none to me. The answer to a probabilities problem CAN depend on the phrasing... if the change in phrasing changes the problem. In your case I don't see how it does. Just because there are two options doesn't mean they have equal probabilities, and the odds of "anyone else" dying are the same as the odds of "someone else" - if anyone is the collective, it's a collective that has much greater odds of one of its component parts dying than of the friend dying. The odds are 6999999999/7000000000. It's like someone is shooting a very inaccurate gun that will hit a random place in a room containing an elephant and a mosquito. The elephant and the mosquito aren't equally likely to get hit.

I always think of these type of things as 50/50, because ultimately, you can re-do that event 1,000 times over and kill your friend in every instance. Because of this fact, the 1/7 BIL becomes irrelevant.
That may be an accurate depiction of the psychological realities, but it doesn't make 1/7 BIL irrelevant, it makes all probabilities irrelevant. So I don't know where you get the 50/50. When I'm seeing things that way I usually conceptualize it as the "probability" of every outcome being 1. (because they all have a chance of happening, and once they've happened they'll have completely happened, not 1/7 BIL happened). But that has nothing to do with actual probabilities.
 

blankedboy

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HerbertTheHamster said:
UNKNOWNINCOGNITO said:
2 friends of mine instead say that the chances are 1 to 7 billion (assuming there are still 7 billion people on earth
should be 1 to 6999999999999. None of you are right.
But that's just under 7 trillion. You have too many 9s.
 

Jimbo1212

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Vhite said:
Jimbo1212 said:
Vhite said:
I agree. If you did it 1000 times and your best friend would be still alive then the truth would be noticable however when you do it just once you have no idea what might happen because there always is chance that it would be him so it would be 50/50.
So so wrong.

It is not him and someone else, but him and 7 billion other people, each just as likely as each other to die making it 1:7000000000

All the maths fail in this thread makes me want to cry =(
I was talking about mentality of this problem rather than mathematical chance...

Er??
What does that even mean? -_-
Mentally should be the same as the mathematical chance. If not, then you are thinking about it in the wrong way.
 

Shoqiyqa

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Page 2:
Shoqiyqa said:
If you can't handle that one this thread [http://www.escapistmagazine.com/forums/jump/18.199542.6545320] should make your scalp fizz.
That link:
Shoqiyqa said:
There are three possibilities in the first stage: car, goat 1 and goat 2.

Once you've chosen:

if you chose goat 1 at one third probability, the host is guaranteed to show goat 2, so the probability that you chose a goat and are looking at goat 2 is one third;

if you chose goat 2 at one third probability, the host is guaranteed to show goat 1, so the probability that you chose a goat and are looking at goat 1 is one third;

if you chose the car at one third probability, the host is going to show goat 1 or goat 2, each at one half probability, so the probability you chose the car and are looking at goat 1 is one sixth and the probability you chose the car and are looking at goat 2 is one sixth.

What you see as outcomes 3 and 4 are, together, only as likely as each of outcome 1 and outcome 2.

If you chose goat 1 and you switch, you are guaranteed to get a car: probability overall is one third.

If you chose goat 2 and you switch, you are guaranteed to get a car: probability overall is one third.

If you chose the car and you switch, you are equally likely to get each of the two goats, so the probability of getting a goat by switching is one sixth for each goat, total one third.

Total probability of getting a car by switching: two thirds.

If you stick, the reveal stage is irrelevant because you're sticking with something you chose at random from three possibilities so your chance of getting the car is one third.

This was covered in The Curious Case Of The Dog In The Night-Time. The main character finds it very frustrating that the supposedly bright people on the radio are incapable of getting their heads around it.

Poking a man who likes to draw explanations yields a pretty picture:



Does that help?
Page 3:
WolfThomas said:
Monty Hall Problem time:
Suppose you're on a game show, and you're given the choice of three doors: Behind one door is a car; behind the others, goats. You pick a door, say No. 1 [but the door is not opened], 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 switch your choice?
 

Vhite

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Jimbo1212 said:
Vhite said:
Jimbo1212 said:
Vhite said:
I agree. If you did it 1000 times and your best friend would be still alive then the truth would be noticable however when you do it just once you have no idea what might happen because there always is chance that it would be him so it would be 50/50.
So so wrong.

It is not him and someone else, but him and 7 billion other people, each just as likely as each other to die making it 1:7000000000

All the maths fail in this thread makes me want to cry =(
I was talking about mentality of this problem rather than mathematical chance...


Er??
What does that even mean? -_-
Mentally should be the same as the mathematical chance. If not, then you are thinking about it in the wrong way.
I know I am. I mean that some people may think this way including OP, I am explaining why.