# CBSE 9th Maths

## Probability

Probability: Let n be the total number of trials and m be a favourable event. The empirical probability P(E) of an event E happening, is given by

• The probability of any certain event is 1.
• The probability of an impossible event ¡s 0.
• 0 ≤ P(E) ≤ 1.

(i) Trial: A single performance of a random experiment is known as a trial.
(ii) Sample space: The set consisting of all possible outcomes of a random experiment is known as sample space.
(lii) Event: A subset of the sample space of a random experiment is called an event.

### Coin Tossing

Consider a fair coin. There are only two possible outcomes that are either getting heads or tails.

Number of possible outcomes = 2
Number of outcomes to get head = 1
The probability of getting head =Number of outcomes to get head/Number of possible outcomes=1/2

### Rolling of Dice

When a fair dice is rolled, the number that comes up top is a number between one to six. Assuming we roll the dice once, to check the possibility of three coming up.

Number of possible outcomes = 6
Number of outcomes to get three = 1
The probability of getting three = Number of outcomes to get three/Number of possible outcomes=1/6