Example 14 - Chapter 13 Class 12 Probability (Term 2)
Last updated at Feb. 15, 2020 by Teachoo
Independent events
Ex 13.2, 6
Ex 13.2, 10 Important
Ex 13.2, 5
Example 10
Example 11 Important
Example 12 Important
Ex 13.2, 15 (i)
Ex 13.2, 8
Ex 13.2, 7 Important
Ex 13.2, 11 (i)
Ex 13.2, 4
Ex 13.2, 13 Important
Ex 13.2, 14 Important
Ex 13.2, 18 (MCQ) Important
Example 13 Important
Example 14 Important You are here
Independent events
Example 14 If A and B are two independent events, then the probability of occurrence of at least one of A and B is given by 1– P(A′) P(B′) Two events A and B are independent if P(A ∩ B) = P(A) . P(B) Probability of occurrence of at least one of A and B = Probability of occurrence of only A + Probability of occurrence of only B + Probability of occurrence of A and B = Probability of occurrence of A or B So, P(at least one of A & B) = P(A ∪ B) = P(A) + P(B) – P(A ∩ B) = P(A) + P(B) – P(A ∩ B) = P(A) + P(B) – P(A) . P(B) = P(A) + P(B) [ 1 – P(A) ] = P(A) + P(B) . P(A’) = 1 – P(A’) + P(B) . P(A’) = 1 – P(A’) [ 1 – P(B) ] = 1 – P(A’) . P(B’) ∴ P(at least one of A & B) = 1 – P(A’) P(B’) Hence Proved Given, A & B are independent So, P(A ∩ B) = P(A) . P(B)