Find the probability of a couple having a baby girlgirl when their fourthfourth child is born, given that the first threethree children were all girlsall girls. assume boys and girls are equally likely. is the result the same as the probability of getting all girlsall girls among fourfour children?

Every single time a person has a baby, it has a 50% chance of being a boy or a girl. Having 3 girls previously will not change anything. These events are independent. So the probability of having a baby girl given that the first 3 were girls is 50% or 1/2 or 0.5.

However, prior to having any kids, the probability of having all girls among 4 children is : 1.2 * 1/2 * 1/2 * 1/2 = 1/16 ... so the result are different.