Probability Rules

The probability of an event A is 0≤P(A)≤1

If S repesents the entire sample space, then P(S) = 1

The compliment of event A is Ac

P(A) + P(Ac) = 1 = P(S)

If events A and B are disjoint, or mutually exclusive, P(A and B) = 0

If A and B are independent, P(A and B) must equal P(A) x P(B) and P(A|B) must equal P(A)

General Addition Rule:

P(A or B) = P(A) + P(B) - P(A and B)

General Multiplication Rule:

P(A and B) = P(A) x P(B|A)

Conditional Probability:

P(A|B) = P(A and B)/P(B)