Given two independent events A and B such that P (A) = 0.3, P (B) = 0.6. Find
(i) $P(A$ and $B)$ ]
(ii) $P$ ( $A$ and not $B$ )
(iii) $P$ ( $A$ or $B$ )
(iv) $P$ (neither $A$ nor $B$ )
It is given that P (A) = 0.3 and P (B) = 0.6
Also, A and B are independent events.
(i) $\therefore \mathrm{P}(\mathrm{A}$ and $\mathrm{B})=\mathrm{P}(\mathrm{A}) \cdot \mathrm{P}(\mathrm{B})$
$\Rightarrow \mathrm{P}(\mathrm{A} \cap \mathrm{B})=0.3 \times 0.6=0.18$
(ii) $P(A$ and not $B)=P\left(A \cap B^{\prime}\right)$
$=P(A)-P(A \cap B)$
$=0.3-0.18$
$=0.12$
(iii) $P(A$ or $B)=P(A \cup B)$
$=\mathrm{P}(\mathrm{A})+\mathrm{P}(\mathrm{B})-\mathrm{P}(\mathrm{A} \cap \mathrm{B})$
$=0.3+0.6-0.18$
$=0.72$
(iv) $P$ (neither $A$ nor $B$ ) $=P\left(A^{\prime} \cap B^{\prime}\right)$
$=P\left((A \cup B)^{\prime}\right)$
$=1-P(A \cup B)$
$=1-0.72$
$=0.28$