posted by maggie r .
The Smith family has 4 children that are all girls. What is the probability that the next one will be a girl?
You plan on having four children and you want all boys. If you have children, what is the probability you will get four boys?
The prob. that the Smith family's next child will be girl is simply 1/2
In all families with four children the prob that the four children will be all boys is (1/2)^4 = 1/16
Here is a principle involved.
I hope this helps a little more. Thanks for asking.