Revision Notes of Chapter 15 Probability Class 9th Math
Topics in the Chapter- Fundamentals
- Probability
- Complementary Events
- Important Notes for Cards and Probability
- Experiment: An operation which can produce some well defined outcomes.
- Sample Space: It is the total number of possible outcomes of a random experiment.
- Event: Any subset of a sample space is called a event.
- Elementary Event: Each outcome of any random experiment.
- Sure Event (Certain event): An event which always occurs whenever the random experiment is performed.
- Impossible Event: An event which never occurs whenever the random experiment is performed.
- Favourable Event: The cases which ensure the occurrence of an event.
Probability
Probability P(E) of an event E is defined as:
P(E) = Number of favourable outcomes/Total number of outcomes
In short, P(E) = Favourable Event/Sample Space
Complementary Events
An event associated with a random experiment denoted by (not E) which happens only when E does not happen is called the complement of event E.
P(not E) = 1 – P(E)
Important Note
- Sum of the probabilities of all the elementary events of an experiment is 1.
P(E1) + P(E2) + P(E3) + ..................... + P(En) = 1 - Probability of Sure Event is 1.
- Probability of an Impossible Event is 0.
- Probability of any event lies between 0 and 1 (including 0 and 1) i.e. 0 ≤ P(E) ≤ 1.
- 52 cards are divided into 4 suits of 13 cards each.The suits are:
Spade, Hearts, Diamonds and Clubs
- Out of 52 cards, 26 are red in colour and 26 are black in colour.
- In each suit, there is an Ace, a King, a Queen, a Jack, 10, 9, 8, 7, 6, 5, 4, 3 and 2.
- King, Queen and Jack are called Face cards.