Probability Properties
Probability Axioms
1.The probability is positive and less than or equal to 1.
0 ≤ p(A) ≤ 1
2. The probability of the sure event is 1.
p(S) = 1
3.If A and B are mutually exclusive, then:
p(A B) = p(A) + p(B)
Probability Properties
1 The sum of the probabilities of an event and its complementary is 1, so the probability of the complementary event is:
2 The probability of an impossible event is zero.
3 The probability of the union of two events is the sum of their probabilities minus the probability of their intersection.
4 If an event is a subset of another event, its probability is less than or equal to it.
5 If A1, A2, ..., Ak are mutually exclusive between them, then:
6 If the sample space S is finite and an event is S = {x1, x2, ..., xn} then:
For example, the probability of obtaining an even number, when rolling a die, is:
P(even) = P(2) + P(4) + P(6)