Probability

Complementary Events : Two events are said to be complementary if they are only two possible outcomes

If A is an event and B is complementary event then

P(A) + P(B) = 1

Mutually Exclusive Events : Two events that cannot happen at same time

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

Mutually Non Exclusive Events : Two events that occur at same timeP(A or B) = P(A) + P(B) - P(A intersection B)