CBSE Class 9 Maths Chapter 15 Notes Probability
Probability Class 9 Notes Understanding the Lesson
1. Experiment: A procedure which produces some well-defined possible outcomes.
2. Random experiment: An experiment which when performed produces one of the several possible outcomes called a random experiment.
3. Trial: When we perform an experiment it is called a trial of the experiment.
4. Event: The set of outcomes of an experiment to which probability is assigned.
5. The empirical (or experimental) probability P(E) of an event E is given by
\(\mathrm{P}(\mathrm{E})=\frac{\text { Number of trials in which } \mathrm{E} \text { has happened }}{\text { Total number of trials }}\)
So, Probability of not happening an event \(\mathrm{P}(\overline{\mathrm{E}})\)= 1 – P(E)
6. The probability of an event lies between 0 and 1 (0 and 1 are included).
7. Impossible event: An event which never happens.
8. Certain event : An event which definitely happens.