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If the probability for $A$ to fail in an examination is 0.2 and that for $B$ is 0.3 , then the probability that either $A$ or $B$ fail is
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1371 Upvotes
Verified Answer
The correct answer is:
0.44
$P(\bar{A})=0.2, P(\bar{B})=0.3$
$$
\begin{aligned}
& \therefore P(A)=0.8 P(B)=0.7 \\
& \therefore \text { Required probability } \\
&=P(\bar{A}) P(\bar{B})+P(\bar{A}) P(\bar{B})+P(\bar{A}) P(\bar{B}) \\
&=0.2 \times 0.7+0.8 \times 0.3+0.2 \times 0.3 \\
&=0.44
\end{aligned}
$$
$$
\begin{aligned}
& \therefore P(A)=0.8 P(B)=0.7 \\
& \therefore \text { Required probability } \\
&=P(\bar{A}) P(\bar{B})+P(\bar{A}) P(\bar{B})+P(\bar{A}) P(\bar{B}) \\
&=0.2 \times 0.7+0.8 \times 0.3+0.2 \times 0.3 \\
&=0.44
\end{aligned}
$$
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