Question

Let $A=\{1,2,3,4\},$ $B=\{4,5,6,7\},$ $C=\{3,6,9,12\}$ and $D=\{4,8,12,16,20\},$ then $n\left[\right(A\times B)\cap (C\times D\left)\right]$ =

• A. $1$
• B. $2$
• C. $4$
• D. $8$

Answer 1

The correct option is A $1$

$(A\times B)\cap (C\times D)=(A\cap C)\times (B\cap D)=\left\{3\right\}\times \left\{4\right\}=\left\{\right(3,4\left)\right\}$