A woman has two kids. One is a boy. What are the odds the other is a boy?

But if one of the kids is a boy, and the other one is a boy, then both are boys.

Damn it Opeth. You should have worded your question better. In that case, I stick to 33% then.

It's 50%! Why are you making everything so complicated!
B/B
B/G
are the only options we have...
plus the qusetion is, "What are the chances of the next child being a boy?"
This thread is crawling up my veins... :f6:

Damn it Opeth. You should have worded your question better. In that case, I stick to 33% then.

If I worded it better this thread would not have been as fun.

It's 50%! Why are you making everything so complicated!
B/B
B/G
are the only options we have...
plus the qusetion is, "What are the chances of the next child being a boy?"
This thread is crawling up my veins... :f6:

How many times must i say this... NO ><

BG and GB are separate options and along with BB that's three options

saying that BG and BB are the only options makes the assumption that you know that the younger child is a boy. It could be either the younger child or the older child. Go read through page 3, follow the link, read, and gtfo with failed intuition. <<

Seriously, i don't normally get mad, but I already explained why people who said 50% are wrong. So go back and try to actually read through the thread before posting. >>

Damn it Opeth. You should have worded your question better. In that case, I stick to 33% then.

How about like this:

Your friend has two kids. One of them is named Nathan after his father. What are the odds the other one is a boy?

How many times must i say this... NO ><

BG and GB are separate options and along with BB that's three options

saying that BG and BB are the only options makes the assumption that you know that the younger child is a boy. It could be either the younger child or the older child. Go read through page 3, follow the link, read, and gtfo with failed intuition. <<

Seriously, i don't normally get mad, but I already explained why people who said 50% are wrong. So go back and try to actually read through the thread before posting. >>

actually you are wrong, the way the question is worded doesnt mean what are the chances both are boys which is 33%. it is, the other is a boy. i explained why it is 50% acording to mendelian genetics in a previous post. go back and read it. oh and add me to BL shouri

How about like this:

Your friend has two kids. One of them is named Nathan after his father. What are the odds the other one is a boy?

Mother pineappling 50%.

PS Opeth: You'd make a great contract writer.

How about like this:

Your friend has two kids. One of them is named Nathan after his father. What are the odds the other one is a boy?

Scenario 1: The younger child is named Nathan (50%)
- 25% chance that the older child is a boy
- 25% chance that the older child is a girl
Scenario 2: The older child is named Nathan (50%)
- 25% chance that the younger child is a boy
- 25% chance that the younger child is a girl

50%.

With the original phrasing, it can be understood three ways.
1. The question is referring to a particular kid of the two, and states that it is a boy. Therefore, the one not mentioned can either be a boy or a girl => 50%.
(To elaborate, there are four possibilities. The 'one' mentioned in the problem is blue:
B/B
B/B
B/G
G/B
The odds that the other is a boy is 2/4 = 50%.)
2. The question states that exactly one kid of the two is a boy, meaning that the 'other' child must be a girl => 0%.
3. The question states that at least one kid is a boy. Likewise, it can also be understood that the woman has at least two kids in the first place => indeterminate.

This is fun.

actually you are wrong, the way the question is worded doesnt mean what are the chances both are boys which is 33%. it is, the other is a boy. i explained why it is 50% acording to mendelian genetics in a previous post. go back and read it. oh and add me to BL shouri

If one is a boy and the OTHER is a boy, then both are boys.

And to the above.

B/B
B/B

these two are the same. The bottom states that the older one is a boy, which the top also does.

Read

Scenario 1: The younger child is named Nathan (50%)
- 25% chance that the older child is a boy
- 25% chance that the older child is a girl
Scenario 2: The older child is named Nathan (50%)
- 25% chance that the younger child is a boy
- 25% chance that the younger child is a girl

50%.

With the original phrasing, it can be understood three ways.
1. The question is referring to a particular kid of the two, and states that it is a boy. Therefore, the one not mentioned can either be a boy or a girl => 50%.
(To elaborate, there are four possibilities. The 'one' mentioned in the problem is blue:
B/B
B/B
B/G
G/B
The odds that the other is a boy is 2/4 = 50%.)
2. The question states that exactly one kid of the two is a boy, meaning that the 'other' child must be a girl => 0%.
3. The question states that at least one kid is a boy. Likewise, it can also be understood that the woman has at least two kids in the first place => indeterminate.

This is fun.

Let's analyse each sentence:

A woman has two kids.
Should be easy enough. The woman does not have 1 kid or 3 kids, but 2 kids.

One is a boy.
This is rather cryptic:
First thing about the sentence is that we don't have any information about which kid it is, so it could be either the first or the second kid.
Now, the second thing about the sentence is that it states the gender of this kid. But was this gender picked out randomly, or with intention? Was the intention to state that one of these woman's kids are a boy, or was it to state that one of the kids have xx or xy gender?

What are the odds the other is a boy?
Easy enough. If given the condition in the sentence before this, what is the probability that the other kid is a boy? It also backs up that the woman has two kids, but this should be clear enough already.

If the kid was picked out randomly, that would mean that either child X or child Y was chosen on beforehand. This gives your four possibilities, and therefore 50% chance.

If the kid was picked out based on gender, that would mean that there's 33% chance, based of all the other pages.

3. The question states that at least one kid is a boy. Likewise, it can also be understood that the woman has at least two kids in the first place => indeterminate.

This isn't really indeterminate. Say we have N kids, and one of these is a boy. That gives us 2^N - 1 different combinations, as we have to remove the all-girl-possibility. Let us now assume that the "other" is taken randomly out of the group of remaining kids. If this group has n boys, then the chance you'll choose a boy is n/(N - 1). Summing up these different chances may be explained as the following function:

This thread is still going? ...goddamn. -facepalms-

This thread is still going? ...goddamn. -facepalms-

That's because biologically the answer is 50%.

Statically it's 33%. The question is being ambiguous like Bridget and thus people are still going over the answer.

My goodness all of your %s are wrong. It's not just boy/girl but it's also transvestite. Now fix your %s. f3

*Was pretty sure that all events are independent from each other*

Because of that, I think it's 50%...'course, reading everyone else's posts, I'm getting confused...

Scenario 1: The younger child is named Nathan (50%)
- 25% chance that the older child is a boy
- 25% chance that the older child is a girl
Scenario 2: The older child is named Nathan (50%)
- 25% chance that the younger child is a boy
- 25% chance that the younger child is a girl

50%.

Yes, but assuming 50% of each, these are wrong.

They're not going to name both kids Nathan (well, let's hope) - so the options are these:
Girl/Girl (eliminated)
Boy/Girl (Older child named Nathan)
Girl/Boy (Younger child named Nathan)
Boy/Boy (One child named Nathan)
These 4 scenarios happen with equal likelihood, so the remaining ones all have 1 in 3 chance of happening now that one is gone (due to knowledge that at least one is a boy)

If we assume it's a 50% chance the older or younger child is named Nathan, that means:
- 1/3 + 1/6 the older child is Nathan = 50%
- 1/3 + 1/6 the younger child is Nathan = 50%

That's 1/3 (other child is a girl) + 1/6 (other child is a boy)
Total: 2/3 of the time, the other kid is a girl.


@ClawofBeta, the problem is not that the events are independent, it's that the information given is ambiguous about which event happened.

Yes, but assuming 50% of each, these are wrong.

They're not going to name both kids Nathan (well, let's hope) - so the options are these:
Girl/Girl (eliminated)
Boy/Girl (Older child named Nathan)
Girl/Boy (Younger child named Nathan)
Boy/Boy (One child named Nathan)
These 4 scenarios happen with equal likelihood, so the remaining ones all have 1 in 3 chance of happening now that one is gone (due to knowledge that at least one is a boy)

If we assume it's a 50% chance the older or younger child is named Nathan, that means:
- 1/3 + 1/6 the older child is Nathan = 50%
- 1/3 + 1/6 the younger child is Nathan = 50%

That's 1/3 (other child is a girl) + 1/6 (other child is a boy)
Total: 2/3 of the time, the other kid is a girl.


@ClawofBeta, the problem is not that the events are independent, it's that the information given is ambiguous about which event happened.

rework it with transvestites included....yes, even though it's not common.

rework it with transvestites included....yes, even though it's not common.

I think you need to look up the meaning of Transvestite, you seem confused. I assume you mean Hermaphrodite?

Where is 0%?
I want that one.
You just said "A woman has TWO kids. ONE is a boy. If ONE is a boy then the odds that the other is a BOY when we stated ONE is a boy is zero."
Now if we mean that AT LEAST ONE is a boy, then things are different.
...
In defense here: no one says I have ONE hand. I have TWO ONE HANDS
....


The chance for offspring having a gender is 50%. Unless we already have One boy in which case two boys in a row is 33%.

Let this thread die already please. Everyone's going to keep arguing their own point endlessly and regardless of what you say, no one's ever going to change their minds >>

The problem with the people responding 50%, is that they are counting one option twice.
Consider the order.
When the child that is known to be male is born first
B / G
B / B

When the child that is known to be male is born second
G / B
B / B

However, the "B / B" option has already been covered in the scenario when looking at the first child being male, e.g. B / B.

Discounting this gives 3 possible outcomes
B / G
B / B
G / B

All of which are equally likely to happen. Therefore, its 1/3 chance or 33%.