Given, $P(A)=0.5, P(B)=0.4, P(A \cap B)=0.3$, then $P\left(A^{\prime} / B^{\prime}\right)$ is equal to
Given, $P(A)=0.5, P(B)=0.4, P(A \cap B)=0.3$, then $P\left(A^{\prime} / B^{\prime}\right)$ is equal to
- $\frac{1}{3}$
- $\frac{1}{2}$
- $\frac{2}{3}$
- $\frac{3}{4}$
Solution
Given $P(A)=0.5, P(B)=0.4$ and $P(A \cap B)=0.3$
To Find $P\left(A^{\prime} / B^{\prime}\right)=$ ?
First, we find $P(A \cup B)$.
$
\begin{gathered}
\because P(A \cup B)=P(A)+P(B)-P(A \cap B) \\
=0.5+0.4-0.3=0.6 \\
P\left(B^{\prime}\right)=1-P(B)=1-0.4=0.6
\end{gathered}
$
$\begin{aligned} P(A \cup B)^{\prime}= & 1-P(A \cup B) \\ = & 1-0.6=0.4 \\ \because P\left(A^{\prime} / B^{\prime}\right) & =\frac{P\left(A^{\prime} \cap B^{\prime}\right)}{P\left(B^{\prime}\right)} \\ & =\frac{1-P(A \cup B)}{1-P(B)}=\frac{0.4}{0.6}=\frac{2}{3}\end{aligned}$
Asked in: AP EAMCET 2021 (25 Aug Shift 2)
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