This chapter provides an explanation of probability for processes
with a finite number of possible outcomes. It explains the meaning of
probability, as well as how to calculate probability and odds. It
also examines the relationship between complementary events.

The first section deals with the probability of a single event. It
provides an equation for probability which you will use to calculate
the probabilities of various events.

The second section introduces the concept of complementary events--that
is, events whose probabilities add up to 1. When two events are
complementary, one occurs if and only if the other does not. This
second also discusses the notion of odds and their relation to
probability.

People use probability and odds in many situations -- to decide what
kind of weather to prepare for, whether or not to buy a stock, and how
much to bet when gambling. Probability helps people understand which
choices are safe and which choices are risky. Of course, this task is
much easier when we have fluent knowledge of probability. By learning
about probability, we can learn about the likelihood of future events,
and prepare accordingly.