A man tells you he has two children. He then starts talking about his son. He does not tell you whether the son is the oldest child or the youngest child. What is the probability that his other child is a girl?
1) a man has 2 children
2) ONE of them is a boy...meaning the one child's sex is unknown
3) the question doesnt ask who came first...just that there is an 'other' child...
4) so you take the known, boy, out of the equation...you have one unknown child's sex out of one child...
what are the odds on ONE child's sex being male or female?
50%
If he has 20 children, and talks about 19 of his boys, and does not talk about the 20th, child, what are the odds of that child being a boy or girl?
50%....
1) a man has 2 children
2) ONE of them is a boy...meaning the one child's sex is unknown
3) the question doesnt ask who came first...just that there is an 'other' child...
4) so you take the known, boy, out of the equation...you have one unknown child's sex out of one child...
what are the odds on ONE child's sex being male or female?
50%
If he has 20 children, and talks about 19 of his boys, and does not talk about the 20th, child, what are the odds of that child being a boy or girl?
50%....
if he has ONE child, and does not mention the child's sex, what are the odds of that child being a boy or girl?
50%
10 years later you run into him again, and he mentions he had another child, and you already know he has a boy from 10 years ago...what are the odds this newborn is a boy or girl?
50%
15 years later he runs into you again and mentions he had an illegitemate child out of wedlock 30 years ago and just found out about it, what are the odds on THAT child's sex????
50%
50%
10 years later you run into him again, and he mentions he had another child, and you already know he has a boy from 10 years ago...what are the odds this newborn is a boy or girl?
50%
15 years later he runs into you again and mentions he had an illegitemate child out of wedlock 30 years ago and just found out about it, what are the odds on THAT child's sex????
50%
Lemme ask this then....if the question were to be rephrased to:
A man tells you he has two children. He then starts talking about his son. He does not tell you whether the son is the oldest child or the youngest child. What is the probability that his YOUNGEST child is a girl?
How would you figure the probability on that?
A man tells you he has two children. He then starts talking about his son. He does not tell you whether the son is the oldest child or the youngest child. What is the probability that his YOUNGEST child is a girl?
How would you figure the probability on that?
Um. Sigh. Again, the problem lies in the fact that you know he has
two children, and him pointing out that one of them is male doesn't tell
you if it's the firstborn, or the secondborn - and therein lies the meat
of the problem.
Again, I'm willing to wager any amount that my answer is correct.
And you would lose that amount due to the way it is worded. If the question is phrased "What are the odds that the youngest child is a boy?"
THEN 2/3 would be correct:
GG is eliminated
BG would be a loser
BB would win
GB would win
2/3......2 out of 3 gueses would be a winner....but that IS NOT how the question is worded....
THEN 2/3 would be correct:
GG is eliminated
BG would be a loser
BB would win
GB would win
2/3......2 out of 3 gueses would be a winner....but that IS NOT how the question is worded....
Ok deal.
Here is the original question:
"A man tells you he has two children. He then starts talking about his son. He does not tell you whether the son is the oldest child or the youngest child. What is the probability that his other child is a girl? "
My answer is 2/3. I will bet you $100 I am correct, deal?
