CLASS 7TH | UNIT 5: DATA HANDLING (STATISTICS) | PROBABILITY | REVISION NOTES

Probability is defined as the likelihood or chance that an event will occur. It is defined as the
numerical method of measuring uncertainty involved in a situation.

To understand and measure
the chance, we perform the experiments like tossing a coin, rolling a die and spinning the
spinner etc.

Terms related to Probability:

 Sample space: It is the set of all possible outcomes in an experiment.
 Trial: An action which results in one or several outcomes.
 Experiment: An experiment is defined as an action or process that results in well defined outcomes.
 Event: The collection of some outcomes of the experiment.

Experimental Probability:
 The fraction of times event E is expected to occur.
 The estimated probability ≅ empirical probability for large number of trials.
The empirical probability P(E) of an event E is given as:
P(E) = (Number of trials in which event E has occurred)/(Total number of trials)

Example

If we throw a dice then what is the probability that we will get a 5?

Solution

Favourable outcome = 1 (there is only one possibility of getting 5)

Total no. of possible outcomes = 6 (total six numbers are there on a dice)

Probability of getting 5 = 1/6