# Important term and definition of probability

## Important Terms of Probability

• Experiment: An activity which gives some well-defined outcomes is called experiment “Tossing a coin” gives either head (H) or tail (T), is an experiment.
• Random experiment: It is an experiment, in which we know about all the possible outcomes but not sure about a specific outcome. For e.g. in throwing a dice, possible outcomes are 1, 2, 3, 4, 5, 6 but we are not sure that the no on dice is ‘4’.
• Event: The possible outcomes of a trial are called events. e.g., when a die is rolled, showing the number 1 or 2 or 3 or 4 or 5 or 6 is an event.
• Sure event: When all the outcomes of a random experiment favour an event, the event is called a sure event and its empirical probability is 1.
• Impossible event: When no outcome of a random experiment favours an event, the event is called an impossible event and its empirical probability is 0.
• Sample space: The collection of all possible outcomes in an experiment is called sample space.
• Favourable events: The cases, which ensure the occurrence of an event, are called favourable cases to that event.