$\begin {array} {1 1} (A)\;28\: \% & \quad (B)\;38\: \% \\ (C)\;72\: \% & \quad (D)\;82\: \% \end {array}$

Let $P(A) = \large\frac{20}{100}$

= $ \large\frac{1}{5}$

P(B) = $ \large\frac{10}{100}$

= $ \large\frac{1}{10}$

Since event are independent

$ \therefore P(A \cup B ) = 1-P(A')\: P(B')$

$ \Rightarrow P(A \cup B)=1-\large\frac{4}{5}.\large\frac{9}{10}$

$ = 1-\large\frac{36}{50}$

$= \large\frac{14}{50} = 28 \%$

Ans : (A)

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