The Basics of Probability

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If I flip a coin, what’s the probability of the coin landing on tails?

Figure 1.

Sample Space
A sample space is a collection of all possible outcomes.

The coin can land on either heads or tails. There is a 1 / 2 = .50 (50%) chance of the coin landing on tails.

Probabilities will always be between 0 (0%) and 1.00 (100%).

Impossible Events
An event with a probability of 0 is impossible (it will never occur).

Certain Events
An event with a probability of 1 is certain (it will always occur).