Class 12 Maths Probability Introduction


Probability: probability measures how much chance is there for my expected
result to happen.

Probability = (no. Of favorable outcome)/(total no. Of outcomes)

Example: Let there be a basket with 3 balls: Red, Green, Blue. If I want to pick a Red ball,
we can calculate the probability of picking a red ball.

Total number of possibilities when we pick a ball from the basket = 3 ( The ball we pick can be Red, Green or blue)

Total number of favorable possibility i.e. possibility to get a red ball = 1

Therefore, Probability of getting a red ball, P(R) = 1/ 3

Sample space: set of all possible outcomes of a random experiment is called Sample space. It is denoted by S.

Sample point: each element of the sample space is called the sample point.
Example: for Tossing a coin, the sample space is s={HEAD,TAIL} and and the
element in sample space namely head, or tail, each of them can be called as
a sample point

Event: it is the set of favorable outcome.
Example: if you throw a coin and if you are looking for head, then head is
the favorable outcome.

Mutually Exclusive events: two events are said to be mutually exclusive if
there is no common element between them.

Exhaustive events: the given events are Exhaustive if when I take the
elements in those events forms the given sample space.

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