Definition: Probability

Probability quantifies how likely it is that an event will occur. Probability only takes values between $0$ and $1$, where $0$ denotes no chance of an event to occur and $1$ 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:

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

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

Since there are $2$ white balls, the number of ways to pick a white ball is $2$. The total number of outcomes is $5$ because there are $5$ balls to choose from. This results in a probability of $0.4$.