# Probability Class 10 Notes Maths: Chapter 15

## Probability

**Experiment :**It is a process, resulting in some well-definedoutcomes.**Random Experiment :**In this type of experiment, all the outcomes are known in advance, but the outcome of any specific event is unpredictable.**Outcome :**This is the result of an experiment.**Sample Space :**The sample space is a set of all possible outcomes of a random experimentand is generally denoted by ‘S’.**Event :**An event is an occurrence.- In a random experiment, if there are n elementary events and m are favourable to an event E, then the probability P of happening of E, denoted by P(E) or simply P, is definedas the ratio M/N It is thus, a concept which measures, numerically, the degree of certainty of the occurrence of events. P(E)=Favourable Outcomes/Total Outcomes
- The probability of a sure event is always 1.
- The probability of an impossible eventis always 0.
- The sum of theprobabilities of all theoutcomes of elementaryevents is 1.
**Complementary Events :**For any event E,$$P(E) + P(\text{\={ E}} ) =1, where \text{\={ E}}$$standsfor not E, E and E are calledcomplementary events.- For any event E associated to a random experiment, we have 0≤P(E)≤1.