What is the probability of having three girIs in a row in one family? What is the chance of having a fourth girl?

1 Answer
Dec 25, 2015

#1/8 and 1/2#


The sex of the baby is basically determined by the father depending on whether he gives a X or Y gene for the fusion of the gonosome (23rd pair of chromosomes).

There is hence a 1 in 2 chance (50% or 0,5 probability) of either a boy or a girl on each occasion.

Therefore, by the multiplication principle, the probability of having 3 girls in a row is #1/2xx1/2xx1/2=1/8#.

The sex of the 4th child is independent of the sexes of the previous 3 and hence is once again #1/2#.