# 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.