Two events A and B will be independent, if
(A) A and B are mutually exclusive
(B) P(A'B') = [1 - P(A)][1-P(B)]
(C) P(A) = P(B)
(D) P(A) + P(B) = 1
Solution
Two events A and B are said to be independent, if P(AB) = P(A) × P(B)
Consider the result given in alternative B.
This implies that A and B are independent, if P(A'B') = [1 - P(A)][1-P(B)]
Distracter Rationale
A. Let P (A) = m, P (B) = n, 0 < m, n < 1
A and B are mutually exclusive
C. Let A: Event of getting an odd number on throw of a die = {1, 3, 5}
`P(A) = 3/6 = 1/2`
B: Event of getting an even number on throw of a die = {2, 4, 6}
`P(B) = 3/6 = 1/2`
D. From the above example, it can be seen that,
P(A) + P(B) = 1/2 + 1/2 = 1
However, it cannot be inferred that A and B are independent.
Thus, the correct answer is B.