Question

The probability of happening at least one of the events A and B is 0.6. If the events A and B happens simultaneously with the probability 0.2, then

$P ( \bar { A } ) + P ( \bar { B } ) =$

• A. 0.4
• B. 0.8
• C. 1.2
• D. 1.4

Answer 1

Answer: (C)

1.2

Answer 2

We are given that $P ( A \cup B ) = 0.6$ and $P ( A \cap B ) = 0.2$.

We know that if $A$ and are any two events, then

$P ( A \cup B ) = P ( A ) + P ( B ) - P ( A \cap B )$

$0.6 = 1 - P ( \bar { A } ) + 1 - P ( \bar { B } ) - 0.2$

$\Rightarrow P ( \bar { A } ) + P ( \bar { B } ) = 2 - 0.8 = 1.2$.