Question

If $A$ and $B$ are mutually exclusive events, given that $P\left(A\right)=\frac{3}{5},P\left(B\right)=\frac{1}{5}$, then $P\left(A\text{or}B\right)$ is

• A. $0.8$
• B. $0.6$
• C. $0.4$
• D. $0.2$

Answer 1

The correct option is A $0.8$

Given $A$ and $B$ are mutually exclusive events.
$\Rightarrow P(A\cap B)=0$
$P\left(A\text{or}B\right)=P(A\cup B)$
$=P\left(A\right)+P\left(B\right)-P(A\cap B)$
$=\frac{3}{5}+\frac{1}{5}$
$=\frac{4}{5}=0.8$