8-5: Adding Probabilities8-5: Adding Probabilities8-5: Adding Probabilities8-5: Adding Probabilities

English CasbarroEnglish CasbarroUnit 8Unit 8

Vocabulary Simple event- an event that can not be

broken down into smaller units (rolling a 2) Compound Event- an event made up of

several simple events (rolling an odd number or a number greater

than 5) Mutually Exclusive Events- events that

cannot occur at the same time (rolling a 2 or a 5)

Inclusive Events If it is possible for both situations to occur at the same

time, the events are called inclusive.

For example, it is possible to draw a king or a spade, but it’s also possible that the king IS the spade.

Conditional Probability

This exists where there are dependent events.

Notation: P(B|A) In words: the probability of B, given

that A has happened.

By cross-multiplying, you can see that

P(B|A) · P(A) = P(A and B)