Question

If $A=\{1,3,5,7\},B=\{a,b,c\}$, then $n(A\times B)$ is equal to

• A. $3$
• B. $4$
• C. $12$
• D. $7$

Answer 1

Answer: (C)

If $A$ contains $m$ elements and $B$ contains $n$ elements then $A\times B$ contains $m\times n$ elements.
Here, $n(A)=4,n(B)=3$
So, $n(A\times B)=4\times 3=12$.