Question

If $n(A\cup B)=8,n\left(A\right)=6,n\left(B\right)=4$, then $n(A\cap B)$=

• A. $2$
• B. $4$
• C. $6$
• D. $8$

Answer 1

The correct option is A $2$

$n(A\cup B)=8n\left(A\right)=6,n\left(B\right)=4$

we know that

$n(A\cup B)=n\left(A\right)+n\left(B\right)-n(A\cap B)$
$8=6+4-n(A\cap B)$

$n(A\cap B)=10-8=2$