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### Probability Of Second Girl Child

Probability Of Second Girl Child - 14 july

kukki and fukki are a married couple (dont ask me who he is and who she is) :)

They have two kids, one of them is a girl. Assume safely that the probability of each gender is 1/2.
What is the probability that the other kid is also a girl?

Hint: It is not 1/2 as you would first think.

1. I think it should be zero...............

2. If the probabilities are evens and there is at least 1 girl then of the 4 possibilities (age sequence counts) of Boy & Boy, Boy & Girl, Girl & Girl and Girl & Boy the first gets eliminated (no girl) and only 1 of the remaining 3 has 2 girls so the probability is 1/3.

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4. It is 1/3

Why.

Start off in the beginning with two kids: (B=boy G=Girl) BB, BG, GB, GG
Now add the information that one of them is a Girl "G", so that leaves you with: BG, GB, GG
Therefore, only 1 of the 3 or 1/3 chance is a girl

1. Why are we taking BG and GB, arent they the same?

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6. i think the cases BG and GB both are same so it should be counted as one case.

1. No. It should be different because one meant that the girl is older and the other is younger.

If it is the same, you are saying that the chances for the parents to have a boy and girl as children is only 1/3.

7. Nice!

Here is my blog; caribbean

8. In my opinion the fact that one of the kids is already a girl does in no way affect the probability of the other one being born a girl\boy. I bet this was supposed to be some classic example of conditional probability, but seriously, the way in which the question is put here does not even have a hint of conditionality. One of the kids already IS a girl. Period. No 1/2 chance of that taking place, she's already here.
Now if we were to consider the probability of say, giving birth to 2 girl twins under the condition that one will be a girl - that's a different story.

1. Giving birth to 2 girl twins under the condition that one will be a girl is the same as as the original question except that they may not be twins.

9. But Basic Science (Punnett Squares etc) proves that the answer is 1/2. Plus Boy-Girl and Girl-Boy are the same thing

10. yeah, something is probably not right in the problem statement. running a simple simulation reveals 1/2 as one would expect assuming the gender selection events are independent biologically.

11. yeah, something is probably not right in the problem statement. running a simple simulation reveals 1/2 as one would expect assuming the gender selection events are independent biologically.