AP Stats - Ch. 15

General Addition Rule

for any two events, A and B, the probability of A or B is
P(A U B) = P(A) + P(B) - P(A n B)

Conditional Probability

P(B|A) = P(B n A)/ P(A) (the numerator will always be in the denominator)
it is read as " the probability of B given A"

Generic Multiplication Rule

for any two events, A and B, the probability of A and B is
P(A n B) = P(A) x P(B|A)

Independence (used formally)

Events A and B are dependent when P(B|A) = P(B)

Tree Diagram

a display of conditional events that is helpful in thinking through conditioning