In real time case Probability is the chance where something will happen, but here probability is a mathematical expression that deals with calculating the occurrence of any event.

That means an event which can produce some well defined outcomes but the exact output cannot be predicted in advance.

Experiment

An operation which results in somewell defined outcomes is called as experiment.

Sample Space

The set of all posssible outcomes from a random experiment is called as Sample space.

It is usally denoted by S.

Event

Any subset of a sample space is called an event

Example

(i) When a coin is tossed, sample space S={H, T}

(ii) When two coins are tossed,
sample space S={HH, HT, TH, TT}