An ugly hag accosts you on the street and says to you, "I have two children. At least one of them is a boy."

BG is also eliminated

Why?

1/3

Because you have to set one of them as being the first child. Either BG or GB then has to eliminated as either the first or second represents the already determined sex.

BG and GB represent the order they are chosen, not the order they're determined. the boy can be the first or the second

P(2 boys | at least 1 boy) = P(2 boys and at least one boy) / P(at least 1 boy) = P(2 boys) / P(at least 1 boy) = 0.25 / 0.75 = 33%

mathworld.wolfram.com/ConditionalProbability.html
using first equation

Does this include LGBT possibilities?

BB
BG
GB
GG

GG is eliminated, thus leaving BB, BG, and GB as the only options. the only case where both are boys is BB, therefore there's a 33% chance

The question is not asking for the chance that both children are boys, it is asking for the chance that the other child is a boy. This indicates that the hash was referring to a specific child. The answer must therefore be 1/2. You got trolled.

And they are the same thing, the question makes no mention of "firsts" or "seconds", only the sex of the other child and that one of them is a boy, it's asking if one is boy what is the probability the other is a boy. Meaning GB and BG are the same, the determined boy is obviously and B and the other a girl.

Obviously B*

Fuck off with your semantics riddles, OP. They don't test anyone's intellect.

You are only half right. Regardless of what the question says, the children are distinct physical objects and therefore can be ordered arbitrarily.

The order doesn't matter though, BG and GB give us the same information, the other one is a girl

50%
1/2 is a boy, there are 2 outcomes for the second Schrodinger child. The second Schrodinger child is either a boy or a girl, and is currently in a superposition of both.
Assuming the 2 outcomes are not entangled, then there is a 50% cache for either occurring.

OP please be more specific by setting rules for these threads, ok? otherwise no one will know who is right.

It is never said that the first kid is a boy. OP just played with semantics to make seem so.

Summer sure came early this year.

>What is the probability that her other child is a boy
Other Child: can be B or G. 50%

OP, in order to make it a trick question like you intended, you would have to word the question like so

>What is the probability that both of her children are boys?

In which case, the answer is 33.333%

Did that old bitch just assume that child's gender?

This.

Thread is full of CIS scum.

I challenge her to prove if .999=1

.999 is not equal to 1

You're welcome

>What is the probability that her other child is a boy as well?

THIS QUESTION IS NONSENSE. PROBABILITY IS USED WITH RANDOM EVENTS IN THIS CASE THE OLD HAG EITHER HAS A BOY OR A GIRL BUT IT IS NOT RANDOM SO YOU CAN'T TALK ABOUT PROBABILITY

NEXT

Probabilities are also used to describe the possibility of something unknown, user.

50%
only 2 genders so either second is a boy or girl

NO NO NO PROBABILITY IN THAT CONTEXT IS ONLY USED IN INFORMAL TALK BUT THAT'S NOT MATHEMATICAL PROBABILITY

U SHOULD ASK ABOUT THE ``CONFIDENCE LEVEL'' OR SOMETHING SIMILAR PROBABILITY IS WRONG HERE

Yes it is; if it wasn't, nobody who studied probability would be allowed to believe in a deterministic universe. Non-determinism is not a necessary component of probability theory.

Wrong witchlet.

.999 + .001 = 1

It's not my fault you suffered the curse of non-ellipses

N-NANI?

this

Wrong nerds.

That would only be true if a child was selected at random and then you were asked what the other childs sex is.

However, that is the not the case. In the OP, you have prior information because when OP says "her other child" the subject (ie the child that is not "her other") is already known to be a boy.

The questions "if you select one child at random, what is the likelihood the other is male?" and "if you know that one of the children is male, what is the likelihood that the other is male?" are not the same and have different answers, because in the second place you have more information. The first question the answer is 50% but the second place the answer is 1/3rd. In fact, even if the question was "If the oldest child is male, what is the likelihood that the youngest child is male" would also be different, because you again have more information, thus changing the odds back to 1/2.

Isn't BG and GB the same thing?

No.

To understand better, try imagining both people as unique individuals; lets call them Sam and Ted.

Sam being male while Ted is female is obviously not the same thing as Sam being female while Ted is male. Those are clearly two different states of being and thus statistically separate. The same logic applies even if they are anonymous characters.

A zoologist is traveling through the rainforest when he is bitten by a venomous snake. He knows that only the female of a certain species of frog native to this rainforest secretes the antidote to this venom, on its back. He also knows that males and females of this species look exactly the same, but only the male croaks.

Luckily he sees such a frog a few meters in front of him. But then he hears a croak from a male behind him and turns around to see two frogs of this species a few meters away in the other direction.

Knowing he only has enough time to run in one direction and lick the pair of frogs or the lone frog before the venom kills him, which should he choose and what is his chance of surviving?

lick both.
2 hands, 1 for each frog.

Hard mode: licking female kills you instantly.

Why is that better and what is his chance of surviving if he licks both?

btfo

All these brainlets can't see the answer.

Here's the real answer: The witch is lying.

I agree, what if it's a boy but he identifies as a girl? You must factor this into your calculations or else your a bigoted genderphobe!

Go back to /r9k/ brainlet, we already in both instances that B can't be the "other" (whose sex we are trying to determine) because it HAS to be the "one boy", therefore in both situations we have the same information, the "other" is female

Know that*

You should try actually checking what question I am replying to before making assumptions. The person I replied to didn't even have a basic level understanding of statistical theory and I was explaining it in simple terms.

You do realize that only one person of the two can be a girl right? We KNOW one is a boy, so either BG or GB can be eliminated, depending on if the second or first variable is the "other child"

If you follow what you said then either BG or GB has to be eliminated as only one of the two boys (the one who isn't the "other") can be either a boy or a girl, the other one is known to be a boy.

>this thread
The first child is irrelevant of the question, it's 50%

we already know one of them is a boy. The other is a boy iff both are boys.

>torture the hag
>get the answer without all the speculation

There.

50%

Thread is already up on r9k. My question is, don't certain breeding pairs have a higher probability of giving birth to certain genders?

Ones sex is completely by chance.

Assuming coin flip

G=Girl
B=Boy

GG=25%
GB=25%
BG=25%
BB=25%

75% is the answer

which isn't the case; depends on region, era, demographics etc.

but its 1 - probability of getting a girl ^ 2

Its 1/3
GG is impossible
and BB is being evaluated against the set of valid possibilities

P(BB)/(P(GB)+P(BG) +P(BB))=1/3