A friend has three boys and would like to have a girl. She explains to you that the probability that her next baby will be a girl is very high because the law of averages says that she should have...

A friend has three boys and would like to have a girl. She explains to you that the probability that her next baby will be a girl is very high because the law of averages says that she should have half of each and she already has three boys. Is she correct? Explain.