What you’ll learn to do: understand and calculate geometric probabilities

A couple has decided to keep having children until they have a girl. At that point, they will stop having children.  What is the probability they will have one child? What is the probability that they would not have a girl until the fourth child? And if many couples did this, how many children would there be on average for all the couples? To be able to answer questions like these, you need to understand how to calculate geometric probabilities and the mean and standard deviation of a geometric random variable.