Question

Let $A=\{a,b,c,d\},$ $B=\{b,c,e,f\},$ then $n\left(\right(A-B)\times (B-A\left)\right)=$

• A. $4$
• B. $16$
• C. $8$
• D. $12$

Answer 1

The correct option is A $4$

$A=\{a,b,c,d\},$ $B=\{b,c,e,f\}$
$A-B=\{a,d\},B-A=\{e,f\}$

$\therefore n\left(\right(A-B)\times (B-A\left)\right)=n(A-B)\times n(B-A)=2\times 2=4$