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I thought I was pretty clear, and even wrote it out. The chances are 50%. I disagree with the answer of 1/3. Here it is again: If the younger child is a boy
by wccrawford 15y ago
I thought I was pretty clear, and even wrote it out. The chances are 50%.
I disagree with the answer of 1/3.
Here it is again:
If the younger child is a boy, the older child can be a boy or girl. 50%.
If the older child is a boy, the younger child can be a boy or girl. 50%.
If both children are exactly the same age, the other child can be a girl or a boy. 50%.
Age has absolutely no bearing on sex.
- raldi 15y agoOkay, we're making progress here in figuring out where our thought processes differ. I have two more questions for you: Imagine a stadium with 1000 fathers, each of whom has two children. (It's some kind of convention, I guess.) You say, "Everyone who does not have at least one son, please leave the room." You would expect 750 fathers to remain in the room, correct? Now, assuming you answered yes to that question: Imagine you ask these remaining 750 fathers, "If you have two sons, please raise your hand." Would you not expect 250 of them, or 1/3, to have their hands raised?
- wccrawford 15y agoYes, 750 would remain. (Assuming 50% of kids are boys, and averages actually working out, etc etc.) And yes, I would expect 1/3 of the remaining people to raise their hands, so 250. The original problem does not go through this process, though. It didn't sort through a bunch of people to find some that match, and then start asking questions. It started with group, and some known information about them, and then started asking questions.