## Revision Notes of Chapter 15 Probability Class 9th Math

**Topics in the Chapter**

- Fundamentals
- Probability
- Complementary Events
- Important Notes for Cards and Probability

**Fundamentals**

**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 â€“ 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 â‰¤ P(E) â‰¤ 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.