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QUESTION

If $p(A)=0.2,\ p(B)=0.4$ and $p(A$ or $B)=0.5$, what is $p(A$ and
$B)$?



ANSWER

$p(A$ or $B)=p(A)+p(B)-p(A$ and $B).$

Therefore $p(A$ and $B)=0.2+0.4-0.5=0.1$




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