Question

If $n\left(A\right)=3$ and $n\left(B\right)=5$ then the number of non-injective mappings possible from $B$ to $A$ is

• A. $125$
• B. $243$
• C. $15$
• D. $90$

Answer 1

The correct option is B $243$

Each element of $B$ can be mapped onto any of the three elements of $A.$
$\therefore$ Total no of non-injective functions is $3\times 3\times 3\times 3\times 3=243$