Sample Space |
The set of all possible outcomes of an experiment |
N/A |
Rolling a fair six-sided die: {1, 2, 3, 4, 5, 6} |

Event |
A subset of the sample space representing an outcome |
N/A |
Rolling an even number: {2, 4, 6} |

Probability |
The likelihood of an event occurring |
P(A) = Number of favorable outcomes / Total outcomes |
P(rolling a 3) = 1/6 |

Complement |
The event that does not occur |
P(A’) = 1 – P(A) |
P(not rolling a 3) = 1 – 1/6 = 5/6 |

Union in Probability |
The event that at least one of two events occurs |
P(A ∪ B) = P(A) + P(B) – P(A ∩ B) |
P(rolling an even number or a prime number) = P(even) + P(prime) – P(even ∩ prime) |

Intersection in Probability |
The event that both events occur |
P(A ∩ B) = P(A) × P(B) |
P(rolling an even number and a prime number) = P(even) × P(prime) |

Mutually Exclusive Events |
Two events that cannot occur simultaneously |
P(A ∩ B) = 0 |
Rolling an odd number and an even number |

Independent Events |
Two events that do not affect each other’s likelihood |
P(A ∩ B) = P(A) × P(B) |
Tossing a coin and rolling a die |

Conditional Probability |
The probability of an event given another event |
P(A |
B) = P(A ∩ B) / P(B) |