In everyday life, we come across the statements such as :

(i) Most probably it will rain today

(ii) Richard should have high possibility to get the driving license in this year

(iii) Chances are very high that David will get the job by this month

(iv) I am in doubt that Michel will pass the examination.

(v) Lilly may get the first prize in swimming competition.

In all above statement “most probably”, “high possibility”, “may get”, “chances”, and “doubt”, etc., show the uncertainty of the occurrence of an event.


It is the concept which numerically measures the degree of certainly of the occurrence of an event. In ancient times, probability started with gambling. But, now it is widely used in science, commerce, weather forecasting, etc.

Some terms Related to Probability

Experiment :-  An operation which can produce some well defined outcomes, is called an experiments.

Event : - Each outcome of an experiment is called an event.

Trial :- By a trial we mean performing an experiment.

Sample Space :- In a random experiment, the set of all possible outcomes is called a sample space and it is denoted by S.

Events : - The collection of some or all outcomes in an experiment is called an event. If, E is an event, then clearly, E ⊆ S

Your second block of text...