Lectures 1  3. 
In this chapter we introduce the basic notions random experiment, sample space, events and probability of event. 
By a random experiment, we mean an experiment which has multiple outcomes and one don't know in advance
which outcome is going to occur. We call this an experiment with `random' outcome.
We assume that the set of all possible outcomes of the experiment is
known. 

Definition 1.1. Sample space of a random experiment is the set of all
possible outcomes of the random experiment. 

Example 1.0.1 Toss a coin and note down the face. This is a random experiment, since there are multiple
outcomes and outcome is not known before the toss, in other words, outcome occur randomly.
More over, the sample space is


Example 1.0.2 Toss two coins and note down the number of heads obtained.
Here sample space is
. 

Example 1.0.3 Pick a point `at random' from the interval .
`At random' means there is no bias in picking any point. Sample space is . 