Question

1)If n(A)=7 , n (B)=13,n (A⋂B)=4,then find n(A U B)​

Answer 1

$n(A)=7 , n (B)=13, \\ n (A⋂B)=4, n(A U B) = ? \\ n(A U B) = n(A) + n (B) - n (A⋂B) \\ = 7 + 13 - 4 \\ = 20 - 4 = 16 \\ n(A U B) =16$

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