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. Let's move on to B, all three are boys. Well, once again we look at the pundit square that we created and we look for BBB when all three children are boys. And this is this box here.