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Event and Happening of an event.
Event is a set of one or more outcomes of an experiment. An event is said to have happened if the outcome is the result of the experiment. e.g. In the experiment of tossing of an coin there are two outcomes head and tail. Two events A and B can be defined as follows:
Event A: Head shows up in the experiment of tossing of a coin.
Event B: Tail shows up in the experiment of tossing of a coin.
Now if head shows up, then we can say that event A has happened.
Probability of an event A is denoted by P(A).
Set of all possible outcomes of an experiment is called as sample space.
If happening of one event changes the probability of another event then those events are said to dependent events.
If happening of one event does not change the probability of another event then those events are said to be independent events.