Originally posted by wolfgang59I'm going to stick my neck out here and say the probability is 1/3?
I posted a similar problem on here a couple of years ago, if you
remember that don't contribute, just sit back and enjoy the discussions!
I phone a work colleague up and his daughter answers the phone. He has
previously told me that he has two children at home, I had no idea he had
a daughter. What are the chances that the other child is also a girl?
Originally posted by joe shmoYou know the first child is a girl.
So... before the phone call the probability that both of the children were girls was 1/4.
After the phone call the probability that both of the children are girls is 1/3 and the probability the the other child is a girl is 1/2.
Is this a correct line of reasoning, or not?
Originally posted by deriver691/3 is incorrect. Think again.
Of course if you phone the work colleague up somewhere that is not his home it could be one of his 5 children that have left home.
If you have four two children families BB, BG, GB, GG. You take a random sample of one by for instance phone. There is only one case in which the other child matches your sample (and one case which is clearly excluded by the result of the sample). So I am still sticking with 1/3.