Logic riddle:

[Fort Fun Indiana]

A sibling can be either male or female

Probability is 50/50 it is a female

The sex of the other sibling is irrelevant

Tomorrow it will either rain or it will not rain.

Does that mean chance of rain tomorrow is 50/50? Nope...

 

[Fort Fun Indiana]

norwegen touched on an important part of the riddle:

You do not know if this is the younger or older sibling in front of you.

 

[deannalw]

A sibling can be either male or female

Probability is 50/50 it is a female

The sex of the other sibling is irrelevant

I agreed with you, but if I find out you're wrong, I'm gonna take it back all sneaky like.

 

[Grumblenuts]

I'm sticking with not enough info then because she still may have more than one sibling.

 

[okfine]

Yes, you guys can't even struggle through a simple math problem without your fetish taking over your senses. I did see that coming.

The only hard part of this type of mathematics is freeing yourself from preconceptions and mistaken assumptions. Understanding what information you have and don't have, and discerning what you can and cannot correctly infer from it.

The population ratio of women to men is 50% so it makes that figure most likely with the information given.

 

[Fort Fun Indiana]

I'm sticking with not enough info then because she still may have more than one sibling.

Sorry for the confusion.

Only one sibling.

 

[rightwinger]

Tomorrow it will either rain or it will not rain.

Does that mean chance of rain tomorrow is 50/50? Nope...

Sex is binary
Probability of rain is not

 

[Fort Fun Indiana]

The population ratio of women to men is 50% so it makes that figure most likely with the information given.

Maybe try it this way:

An infinite deck of cards, but half are red and half are black.

I select two cards at random, and I hold them behind my back.

I show you one of them. It is red.

What is the probability the other card I hold is also red?

 

[Fort Fun Indiana]

Sex is binary
Probability of rain is not

Just as the probability of both being female or not is not binary. If you have two kids, the probability both are female is 25%.

 

[rightwinger]

Just as the probability of both being female or not is not binary. If you have two kids, the probability both are female is 25%.

Not if you already know one is female

 

[Fort Fun Indiana]

Not if you already know one is female

Correct, in that the probability is no longer 25%

Incorrect, in that it does not now make it a two-member set of equally likely possibilities.

 

[rightwinger]

Correct, in that the probability is no longer 25%

Incorrect, in that it does not now make it a two-member set of equally likely possibilities.

One member is already set
The other member is 50/50

 

[deannalw]

I'm going with elevendy-seven%.

Who's with me???

 

[Fort Fun Indiana]

One member is already set
The other member is 50/50

This is where your fundamental error lies. Both members are "already set". The coins have already been flipped.

Else, this problem would then be reduced to, "The girl's mother is about to have another baby. Will it be male or female?"

In this case, you know you have the older sibling in front of you.

In my riddle, you do not have this information.

 

[Grumblenuts]

Else. This problem would be reduced to, "The girls mother is about to have another baby. Male or female?"

It would be just the "baby" for all fetus worshippers here. LOL

 

[rightwinger]

This is where your fundamental error lies. Both members are "already set". The coins have already been flipped.

Else, this problem would then be reduced to, "The girl's mother is about to have another baby. Will it be male or female?"

In this case, you know you have the older sibling in front of you.

In my riddle, you do not have this information.

Doesn’t matter

We know the sex of one
Don’t know the sex of the other
Makes it 50/50

 

[Grumblenuts]

He's saying the odds of having a boy and a girl are higher than having two girls regardless. Sequential vs combinational logic. Given one then the other..

 

[Baron Von Murderpaws]

More questions than information given, so not enough to go on.

 

[Winco]

You're a liberal. Are we assuming there are only two sexes?

I agree that there are only two sexes.

I will also acknowledge a person who identifies as gay as 'just another one of us' with NO MENTAL issues, as some RWI's suggest.
Gays have been among the non gay, as long as humans have existed.
I just choose to treat the gay the same as I treat the non-gay.
Many RWI's have a problem doing that, they openly tell us that, (well at least the vocal on USMB) and the very few bigots I know.

So, what's the next concern you have about how I feel about the gay community?
In case you missed the point, "I have no problem with anyone that identifies as gay."

Is trans your next question.
To that I will answer the exact same way.
Deal with it and quit being so angry.

 

[Dadoalex]

You are sitting in the park and meet a girl. She says she has one sibling.

What is the probability her sibling is also female?

(Assume no identical twins)

Sorry. error vote.

This is not a dependent probability so the probability is approximately 50%.

Girl
Sibling can be girl or boy approximately 50% probability.