Question

If $n\left(A\right)=10,n\left(B\right)=12$ and $n(A\cap B)=6$ then find $n(A\cup B)$

Answer 1

We have $n(A\cup B)=n\left(A\right)+n\left(B\right)-n(A\cap B)$

$n(A\cup B)=10+12-6$

$\therefore n(A\cup B)=16$