
Probability of a girl?
Please help me understand conditional probability.
Q: Find the probability of a couple having a baby girl when their fourth child is born, given that the first 3 children are girls.
A: I think the answer is 0.5. Because regardless of the situation the probability will always be 0.5 as each event is independent.
How can I solve this problem in terms of P(BA)=P(A and B)/P(A) (Headbang)


Just a comment on the problem
Both crazydeo and Soroban assume that the genders of the children are (statistically) independent. I think this is very likely true, but it is not automatically so. One can imagine biological mechanisms which would result in nonindependence.
(According to this web page
Houghton Mifflin Science for Families: Cricket Connections
there was an article in "Chance" which concluded there is no compelling evidence for nonindependence.)