There is a 50% chance of it being a boy or a girl also known as 1/2
So the first baby has a 1/2 chance, same for the second, and third, Which means that there is a 1/2, then another 1/2 and another 1/2. So you would have to multiply them all, 1/2*1/2*1/2 = 1/8. For the girl, again, it is 1/2 chance of being a girl, while the other 1/2 is a boy. So 1/8*1/2 is 1/16. So the probability so the women having 3 boys then a girl, is 1/16.
