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Home  >>  CBSE XI  >>  Math  >>  Probability
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If E and F are events .Such that $P(E)=\large\frac{1}{4}$$,P(F)=\large\frac{1}{2}$ and P(E and F)=$\large\frac{1}{8}$.Find P( E or F)

$\begin{array}{1 1}(A)\;\large\frac{5}{8}\\(B)\;\large\frac{7}{8}\\(C)\;\large\frac{3}{8}\\(D)\;\large\frac{1}{8}\end{array} $

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1 Answer

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  • $P(E \cup F)=P(E)+P(F)-P(E \cap F)$
P(E) =$\large\frac{1}{4}$
P(F)=$\large\frac{1}{2}$
P(E and F) (ie) $P(E \cap F)=\large\frac{1}{8}$
P( E or F)=$P( E \cup F)$
$\Rightarrow P(E)+P(F)-P(E \cap F)$
$\Rightarrow \large\frac{1}{4}+\frac{1}{2}-\frac{1}{8}$
$\Rightarrow \large\frac{2+4-1}{8}$
$\Rightarrow \large\frac{5}{8}$
$\therefore$ P( E or F)=$\large\frac{5}{8}$
Hence (A) is the correct answer.
answered Jul 1, 2014 by sreemathi.v
 

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