Question

If $A$ and $B$ be two sets containing $4$ and $12$ elements respectively, what can be the minimum number of elements in $A\cup B$? Find also, the maximum number of elements in $(A\cup B)$.

Answer 1

Given

$n\left(A\right)=4$

$n\left(B\right)=12$

minimum number of element in $A\cup B$ $=12$ (A is subset of B}

maximum number of element in $A\cup B$ $=12+4=16$ [all element taken in both set A and B and elements in both sets are different]