TOPICS

Formulae

Probability

1.Impossible event :The empty set 2.Sure event:The whole sample space 3.Complementary event or ‘not event’ :The set A′ or S – A 4.Event A or B:The set A ∪ B 5.Event A and B:The set A ∩ B 6.Event A and not B:The set A – B 7.Mutually exclusive event:A and B are mutually exclusive if A ∩ B = φ 8.Exhaustive and mutually exclusive events:Events E1, E2,..., En are mutually exclusive and exhaustive if E1 ∪ E2 ∪ ...∪ En = S and Ei ∩ Ej = φ V i ≠ j

1. Probability of an event P(A) = n(A)/n(S), where n(A) = number of elements in the set A, n(S) = number of elements in the set S. 2. If A and B are any two events, then P(A or B) = P(A) + P(B) – P(A and B) equivalently, P(A ∪ B) = P(A) + P(B) – P(A ∩ B) 3. If A and B are mutually exclusive, then P(A or B) = P(A) + P(B) 4. If A is any event, then P(not A) = 1 – P(A)

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