Probability - Revision Notes

 CBSE Class 10 Mathematics

Revision Notes
CHAPTER 15
PROBABILITY

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(i) Probability
(ii) Miscellaneous Questions

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1. The Theoretical probability of the occurence of an event E written as P(E) is P(E)=NumberofoutcomesfavourableofENumberofallpossibleoutcomesoftheexperiment$\frac{NumberofoutcomesfavourableofE}{Numberofallpossibleoutcomesoftheexperiment}$
    
2. Experiment: An activity which ends in some well defined outcomes is called an experiment.
3. Trial: Performing an experiment once is called a trial.
4. Event: The possible outcomes of a trial is called an event.
5. Sure event: An event whose occurence is certain is called a sure event.
6. The sum of the probability of all the elementary events of an experiment is 1.
7. The probability of a sure event is 1 and probability of an impossible event is 0.
8. If E is an event, in general, it is true that P(E) + P (E ¯¯¯¯¯) = 1.$\text{P}\left(\text{E}\right)+\text{ P }\left(\overline{\text{E }}\right)=\text{ 1}.$   [P(E¯¯¯¯)=P(notE)]$[P(\overline{E})=P(notE)]$
9. From the definition of the probability, the numerator is always less than or equal to the denominator therefore 0≤P(E)≤1$0\le P(E)\le 1$.