CBSE Class 9 Mathematics Probability Notes Set A

Chapter 15

Probability

Chapter Notes

Top Definitions

1. Probability is a quantitative measure of certainty.

2. Any activity associated to certain outcome is called an experiment.

e.g. (i) tossing a coin (ii) throwing a dice (ii) selecting a card.

3. A trial is an action which will result in one and several outcomes.

4. An event for an experiment is the collection of some outcomes of the experiment. E.g (i) Getting a head on tossing a coin (ii) getting a face card when a card is drawn from a pack of 52 cards.

Top Concepts

1. Probability of an event lies between 0 and 1.

2. Probability can never be negative.

3. A pack of playing cards consist of 52 cards which are divided into 4 suits of 13 cards each. Each suit consists of one ace, one king, one queen, one jack and 9 other cards numbered from 2 to 10. Four suits named spades, hearts, diamonds and clubs.

4. King, queen and jack are face cards.

5. The two possible outcomes of tossing a coin are head and tail.

6. The sum of the probabilities of all elementary events of an experiment is 1.

Top Formulae

1. The empirical (experimental) probability of an event E denoted as P(E) is given by:

 P(E) =Number of trialin which the event happenend /TotalNumber of Outcomes 

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