Probability is the branch of mathematics concerned with analyzing the chance that a particular event will occur. The basic purpose of probability is to attempt to predict the likelihood that something will or will not happen. Probability can be calculated on the basis of observing the number of actual outcomes and the number of possible total outcomes.

For example, if the Smith family has three girls, and is expecting a fourth child, is there an equally likely chance of having a boy or a girl? Many people feel the next child "is bound to be a boy" because there are already three girls in the family. What do you think? Discuss this question in your group. Be prepared to explain your answer to the class. Next discuss what you think the approximate percentage of males and females born yearly is worldwide.

Statements involving probability are quite common in everyday situations, and it is important to be aware of them. Many different devices can be used to investigate the study of chance, including number cubes, drawing a card from a deck, picking a colored cube from a bag, or even tossing a coin. Sometimes we want to make predictions about the probability of an event based on a large collection of data. Computers can be used to help collect and analyze large amount of data easily and in a short amount of time. Go to "Investigation I" to try it out for yourself!