Logic riddle:

[Meathead]

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.

I had one question for the OP. We agree that sex is binary. Still, I am unsure if the OP agrees and that has bearing on the answer.

As for the rest of your post, I don't give a rat's ass.

 

[Dadoalex]

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.

That does not matter.

The probability of 2 girls in succession or two boys in succession is 25%. Dependent probability.
Since we already know the sex of the person in the park (female) the sex of the other is the question to be answered.
The siblings sex is independent of the girl's sex.
Therefore, like rolling a die 1000 times, the result of next roll will be independent of the previous 1000 rolls, no matter their value.
This is an independent probability and, whether the sibling is born or not that probability is 50%.

Just noting, a sibling is a person who's already born otherwise the question should have been phrased around the future sibling.

 

[norwegen]

The probability of 2 girls in succession or two boys in succession is 25%.

Yea, that's the premise in the OP.

 

[Winco]

The math challenged are tough to argue with.
Because they don't understand the mistakes they are making, thus they think they are correct, when in reality their thinking is flawed.

Twain, "Never argue with an idiot. They will drag you down to their level, then beat you with experience."

 

[Fort Fun Indiana]

Doesn’t matter

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

Sorry, but no.

 

[Fort Fun Indiana]

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.

No.

 

[Fort Fun Indiana]

That does not matter.

The probability of 2 girls in succession or two boys in succession is 25%. Dependent probability.
Since we already know the sex of the person in the park (female) the sex of the other is the question to be answered.
The siblings sex is independent of the girl's sex.
Therefore, like rolling a die 1000 times, the result of next roll will be independent of the previous 1000 rolls, no matter their value.
This is an independent probability and, whether the sibling is born or not that probability is 50%.

Just noting, a sibling is a person who's already born otherwise the question should have been phrased around the future sibling.

No.

 

[AzogtheDefiler]

33.3%

 

[occupied]

I don't like this one. Logic puzzles should have a definitive answer.

In coin flips you could ask: What are the odds two coin flips will both result in heads? 1/3
or
What are the odds the second coin flip will be heads? 1/2

 

[Fort Fun Indiana]

I don't like this one. Logic puzzles should have a definitive answer.

In coin flips you could ask: What are the odds two coin flips will both result in heads? 1/3
or
What are the odds the second coin flip will be heads? 1/2

There is one, correct answer to the riddle.

You ordered your coin flips.

If I had asked, "She has a younger sibling. What is the probability the younger sibling is female?"...

...that would be a different riddle.

 

[norwegen]

I don't like this one. Logic puzzles should have a definitive answer.

In coin flips you could ask: What are the odds two coin flips will both result in heads? 1/3
or
What are the odds the second coin flip will be heads? 1/2

The odds of two coin flips resulting in two heads is 1/4.

It's the same puzzle as the OP.

 

[Fort Fun Indiana]

Should I describe the solution? I think I will wait a bit more.

 

[occupied]

The odds of two coin flips resulting in two heads is 1/4.

It's the same puzzle as the OP.

I get it now. Not really at my best right now. Herbally impaired.

 

[Fort Fun Indiana]

I had one question for the OP. We agree that sex is binary. Still, I am unsure if the OP agrees and that has bearing on the answer.

As for the rest of your post, I don't give a rat's ass.

Nah, you just don't want to tackle the riddle. You're not fooling anyone.

 

[Winco]

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?

There have been many correct responses and many that are not correct.
There has been many incorrect assumptions.

So, let's be as transparent as possible.
We are talking about two children, same mother and father, no adoption, no step-children, no transgender flip, just a normal (R) family. Correct.
Not that this ^^^^^^ really matters, but some will try to spin/flip the transparency with spin.
We also must be talking about the probability of M versus F birth is exactly 50/50.
Which it isn't, but you can't even give an answer w/out this knowledge.

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

In this case, there are already two children, and two children only. Who is younger or older or twins is irrelevant. She already has a sibling, so we are not talking about dead siblings or future siblings.

If two Children. In order. Then......

B/B
B/G
G/B
G/G

Each is 25%.

BUT.......Since it is established that one of them is ALREADY a G.
The B/B possibility Doesn't exist.
This would only apply if you were asking about two future children w/out either of them having being born YET.

So, if ONE of them is a G,
then the only possibilities are......
B/G
G/B
G/G

each 33.3Repeating %..........The G/G is 1/3.

 

[Fort Fun Indiana]

33.3% is the correct answer. As simply as I can put it:

There are four equally.possible permutations of two siblings:

BB
BG
GB
GG

If one permutation is eliminated from the sample space, three equally likely permutations remain:

BG
GB
GG

So the problem is basically asking:

What is the probability that, when choosing at random from this sample space, you choose GG?

The probability is 33.3%

 

[Fort Fun Indiana]

The math challenged are tough to argue with.
Because they don't understand the mistakes they are making, thus they think they are correct, when in reality their thinking is flawed.

Twain, "Never argue with an idiot. They will drag you down to their level, then beat you with experience."

This problem digs deeper than math knowledge.

I have asked a room of math majors this question, with more than half of them getting it wrong on their first attempt.

 

[Fort Fun Indiana]

The siblings sex is independent of the girl's sex.

Correct, inasmuch as her sex being chosen at fertilization. But the two independent trials have already occurred. Both coins have already been flipped.

While one coin flip does not affect the other, the sample space is made up of the permutations of the two coin flips.

4 equally occuring permutations:

HH
HT
TH
TT

If you flip the two coins and record the results of both flips (a permutation) the occurrence of each permutation will trend to 25% of all permutations.

For simplicity, you can reduce the sampe space to four permutations, each occuring once.

{HH, HT, TH, TT}

Now, consider ONLY the coin flip pairs where at least one coin is tails.

{HT, TH, TT}

Now choose at random from this sample set. What is the probability you choose the TT permutation?

1/3.

 

[Meathead]

33.3% is the correct answer. As simply as I can put it:

There are four equally.possible permutations of two siblings:

BB
BG
GB
GG

If one permutation is eliminated from the sample space, three equally likely permutations remain:

BG
GB
GG

So the problem is basically asking:

What is the probability that, when choosing at random from this sample space, you choose GG?

The probability is 33.3%

Bull, if you roll a six five times,what are the chances of rolling a six on the sixth roll?

If you can figure that out, you have your answer, gender fluidity disregarded of course.

Since this then is binary, it is something like 49.8% sister and 50.2% brother given the small discrepancy of frequency at birth.

What Is the Gambler's Fallacy?​

The gambler's fallacy, also known as the Monte Carlo fallacy, occurs when an individual erroneously believes that a certain random event is less likely or more likely to happen based on the outcome of a previous event or series of events. This line of thinking is incorrect, since past events do not change the probability that certain events will occur in the future.

Gambler's Fallacy: Overview and Examples

The gambler's fallacy is an erroneous belief that a random event is less or more likely to happen based on the results from a previous series of events.

www.investopedia.com

 

[Fort Fun Indiana]

Bull, if you roll a six five times,what are the chances of rolling a six on the sixth roll?

If you can figure that out, you have your answer, gender fluidity disregarded of course.

Since this then is binary, it is something like 49.8% sister and 50.2% brother given the small discrepancy of frequency at birth.

What Is the Gambler's Fallacy?​

The gambler's fallacy, also known as the Monte Carlo fallacy, occurs when an individual erroneously believes that a certain random event is less likely or more likely to happen based on the outcome of a previous event or series of events. This line of thinking is incorrect, since past events do not change the probability that certain events will occur in the future.

Gambler's Fallacy: Overview and Examples

The gambler's fallacy is an erroneous belief that a random event is less or more likely to happen based on the results from a previous series of events.

www.investopedia.com

No. Incorrect.