Session Objectives

• To study what is probability

• To study the various approaches to probability

• To study some probability rules

In this Chapter we will get familiar with some more probability rules like addition, multiplication, general rule and their applications. We will also study the Bayes’ theorem of probability.

Basic Probability Concepts

Experiment: - Any operation / process that results in two or more outcomes is called an experiment.

Example: rolling an unbiased die, tossing a coin

Random Experiment: - Any well-defined process of observing a given chance phenomena through a series of trials that are finite or infinite and each of which leads to a single outcome is known as a random experiment.

Example:- drawing a card from a pack of 52 cards, drawing a ball from a bag containing a given number of red, blue and white balls

Possible Outcome: - The result of a random experiment is called an outcome.

Example:- picking a red ball from a bag containing red and white balls, getting an ace from a pack of well-shuffled 52 cards

Event: - An event is one or more possible outcomes of an experiment or a result of a trial or an observation.

Example:- getting a head on tossing a fair coin

Elementary Event: - A simple or elementary event is a single possible outcome of an experiment. A simple event cannot be further subdivided into a combination of other events.