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# If two events A and B $P( A \cup B ) = 0.5\: and \: P(A \cap B ) = 0.4$ then $P(A')+P(B')=$

$\begin {array} {1 1} (1)\;0.8 & \quad (2)\;1.25 \\ (3)\;1.1 & \quad (4)\;none\: of \: these \end {array}$

$P(A)+P(B)=P(A \cup B ) + P(A \cap B)$
$= 0.5 + 0.4=0.9$
$\therefore P(A')+P(B') = 1- P(A)+1-P(B)$
$= 2-0.9$
$= 1.1$
Ans : (3)