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In a daily life come across the words like probably, likely, may be, chance and hope etc. All these are synonyms to probability.

**Probability:**

Probability is defined as the numerical method of measuring uncertainty involved in a situation.

It is widely used in the study of mathematics, statistics, gambling, physical science, biological science, weather forecasting, finance etc. to draw conclusions.

**Experiment:**

An experiment is defined as an action or process that results in well defined outcomes.

**Random experiment:**

An experiment, in which we know all the results, but cannot predict them, is called a random experiment.

**Outcomes:**

The possible results of an experiment are called the outcomes.

**Event:**

A combination of outcomes is called an event.

**Elementary event**

An outcome of a random experiment is called an elementary event.

**Compound event**

It is an event obtained by combining two or more elementary events associated to the random experiment.

**Occurrence of an event**

An event A associated to a random experiment is said to occur if any one of the elementary events associated to the event A is an outcome.

**Negation of an event **

Every event A associated with a random experiment we define an event " not A" which occurs when and only when A does not occur. The event "not A" is called the negation of event A and is denoted by $\stackrel{\text{\_}}{\text{A}}$.

For example when an unbiased die is rolled getting an even number is an event. In this event the outcomes are {2,4,6}.

When an experiment is performed, outcomes are said to be equally likely, if each outcome has the same chance of occurring.

Probability of event E is defined as :

Probability of an event = $\frac{\text{No.of favourable outcomes}}{\text{Total number of outcomes}}$.

For any event A, 0 â‰¤ P(A) â‰¤ 1.

And P(A) + P($\stackrel{\text{\_}}{\text{A}}$) = 1.

In a daily life come across the words like probably, likely, may be, chance and hope etc. All these are synonyms to probability.

**Probability:**

Probability is defined as the numerical method of measuring uncertainty involved in a situation.

It is widely used in the study of mathematics, statistics, gambling, physical science, biological science, weather forecasting, finance etc. to draw conclusions.

**Experiment:**

An experiment is defined as an action or process that results in well defined outcomes.

**Random experiment:**

An experiment, in which we know all the results, but cannot predict them, is called a random experiment.

**Outcomes:**

The possible results of an experiment are called the outcomes.

**Event:**

A combination of outcomes is called an event.

**Elementary event**

An outcome of a random experiment is called an elementary event.

**Compound event**

It is an event obtained by combining two or more elementary events associated to the random experiment.

**Occurrence of an event**

An event A associated to a random experiment is said to occur if any one of the elementary events associated to the event A is an outcome.

**Negation of an event **

Every event A associated with a random experiment we define an event " not A" which occurs when and only when A does not occur. The event "not A" is called the negation of event A and is denoted by $\stackrel{\text{\_}}{\text{A}}$.

For example when an unbiased die is rolled getting an even number is an event. In this event the outcomes are {2,4,6}.

When an experiment is performed, outcomes are said to be equally likely, if each outcome has the same chance of occurring.

Probability of event E is defined as :

Probability of an event = $\frac{\text{No.of favourable outcomes}}{\text{Total number of outcomes}}$.

For any event A, 0 â‰¤ P(A) â‰¤ 1.

And P(A) + P($\stackrel{\text{\_}}{\text{A}}$) = 1.