# Chapter 3: An Introduction to Probability

**Advanced**Created by: CK-12

Introduction

The concept of probability plays an important role in our daily lives. Assume you have an opportunity to invest some money in a software company. Suppose you know that the company’s past records indicate that in the past five years, the company’s profit has been consistently decreasing. Would you still invest your money in it? Do you think the chances are good for the company in the future?

Here is another illustration: suppose that you are playing a game that involves tossing a single die. Assume that you have already tossed it \begin{align*}10\;\mathrm{times}\end{align*}

Notice that decisions concerning a successful investment in the software company and the decision of not betting \begin{align*}\$ 100\end{align*}

- 3.1.
## Events, Sample Spaces, and Probability

- 3.2.
## Compound Events

- 3.3.
## The Complement of an Event

- 3.4.
## Conditional Probability

- 3.5.
## Additive and Multiplicative Rules

- 3.6.
## Basic Counting Rules