Question

If $n\left(A\right)=6,n\left(B\right)=8$ and $n(A\cup B)=12$, then $n(A\cap B)=$

• A. $6$
• B. $2$
• C. $8$
• D. $12$

Answer 1

Answer: (B)

$2$

We know that $n\left(A\right)+n\left(B\right)=n(A\cup B)+n(A\cap B)$

$n\left(A\right)=6,$ $n\left(B\right)=8$ and $n(A\cup B)=12$

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

$n(A\cap B)=6+8-12=2$