These comprehensive RBSE Class 9 Maths Notes Chapter 15 Probability will give a brief overview of all the concepts.

## RBSE Class 9 Maths Chapter 15 Notes Probability

1. Trial and events : An experiment of any context which must have an outcome out of several outcomes is called a trial and its possible outcomes are called events. For example : Drawing two cards from the deck of 52 cards is a trial and coming queen and king in those cards is an event.

2. Trial and outcome : Trial an action of doing an experiment at once and the results of trial are called outcomes.

3. A random experiment : An experiment which has many possible outcomes but none of them are predictable in advance, is called a random experiment.

4. Event: All the outcomes of a trial are called events. Each of them are events.

5. Favourable outcome : Those outcomes which show the occurence of an event are called favourable outcomes of that event.

6. Sample space : The collection of all possible outcomes of an event is called sample space.

7. Probability : The empirical probability of an event E is defined as :

\(\mathrm{P}(\mathrm{E})=\frac{\text { Number of trials in which the event }(\mathrm{E}) \text { happened }}{\text { Total number of trials }}\)

8. The probability of occurence of any event always lie from 0 to 1, in which both 0 and 1 are included.

9. Sure event : When the probability of occurence of any event is 1, the event is called a sure event.

10. Impossible event : When the probability of occurence of any event is zero, the event is called an impossible event.

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