Examples include probability of flipping a head, rolling a 6 on a single cube, or being born on a Sunday.The likelihood of something happening or being the case.

Outcome: A possible result of an experiment

Sample Space: all the possible outcomes of an experiment

Event: one or more outcomes of an experiment

Probability of an event happening = | Number of ways the event can happen |

Total Number of Outcomes |

Probability of Heads = | Total number of heads |

Total number of coin faces |

Probability of Heads = | 1 |

2 |

This can also be written as 50% or 0.5

Probability of 3 = | Total number of 3's |

Total number of die/cube faces |

Probability of 3 = | 1 |

6 |

This can also be written as 16.67% or 0.1667

We want to find out the probability of picking an orange

Probability of picking an Orange = | Total oranges |

Total fruits |

Probability of picking an Orange = | 5 oranges |

3 apples + 5 oranges + 6 bananas |

Probability of picking an Orange = | 5 |

14 |

This can also be written as 35.71% or 0.3571

A probability of 0 means the event is impossible.

A probability of 1 means the event is certain.

A probability of 0.5 or 1/2 or 50% means the event is equally likely to happen as it is not happen.

A probability greater than 1/2 or 0.5 or 50% and less than 1 is

A probability less than 1/2 or 0.5 or 50% and greater than 0 is

For a Sample Space S (all possible outcomes), P(S) = 1 (since it is all possible outcomes)Sample Space: the set of all possible outcomes or results of that experiment.

Probability of the empty set (event without outcomes) is: P(∅) = 0Empty Set: The set with no elements

∅

Complement of an event: The opposite of an event happening

A^{C}

Event | Complement |
---|---|

Win | Lose |

Rain | No Rain |

Flip heads on a coin | Flip tails on a coin |

P(A') = 1 - P(A)

P(A U A') = 1

P(A) + P(A') = 1

P(A') = 1 - P(A)

Free Probability Calculator - This lesson walks you through the basics of probability like the probability definition, events, outcomes, experiments, and probability postulates

Probability of an event happening = Number of ways the event can happen/Total Number of Outcomes

For an Event A, 0 ≤ P(A) ≤ 1

P(S) = 1

P(∅) = 0

P(A') = 1 - P(A)

For more math formulas, check out our Formula Dossier

For an Event A, 0 ≤ P(A) ≤ 1

P(S) = 1

P(∅) = 0

P(A') = 1 - P(A)

For more math formulas, check out our Formula Dossier

- complement
- The opposite of an event happening

A^{C} - empty set
- The set with no elements

∅ - event
- a set of outcomes of an experiment to which a probability is assigned.
- experiment
- In statistics, a controlled and repeatable process
- likelihood
- how likely a particular population is to produce an observed sample
- outcome
- a possible result of an experiment or trial
- postulate
- A statement accepted as true without proof
- probability
- the likelihood of an event happening. This value is always between 0 and 1.

P(Event Happening) = Number of Ways the Even Can Happen / Total Number of Outcomes - sample space
- the set of all possible outcomes or results of that experiment.
- statistics
- Statistics is a discipline concerned with the analysis of data and decision making based upon data.

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