Definition: Probability

Probability quantifies how likely it is that an event will occur. Probability only takes values between 00 and 11, where 00 denotes no chance of an event to occur and 11 denotes that an event will definitely happen.

A higher probability indicates a greater chance that an event will occur.

Calculating the probability

The probability of an event can be calculated with:

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Suppose that a box contains 2 white and 3 black balls. The probability of picking a white ball is:

P=25=0.4P = \frac{2}{5} = 0.4

Since there are 22 white balls, the number of ways to pick a white ball is 22. The total number of outcomes is 55 because there are 55 balls to choose from. This results in a probability of 0.40.4.

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