So let's move on to A. If a couple decides to have three children, what is the probability that A all three are girls? Now which one of these boxes describes this situation? Well, the only box that describes the situation is the final box where we have a girl the first time around, a girl the second time around and a girl the third time around. And so the probability of that event is simply one 8th. So in part A we simply have one 8th.