Probability based question useful for your interviews

[Balaji]

The probability that at least one of the event A and B occurs is 0.6 . 
if A and B occurs simultaneously with probability 0.2  
then P(A')+P(B')=?

A. 0.4
B. 0.8
C. 1.2
D. 1.4


SOLUTION 

P(A')+P(B') = 2 - [P(A)+P(B)]

= 2 - [0.6+0.2]
=1.2

SO CHOICE C IS CORRECT ANSWER