Let A = {6, 10, 11, 15, 12} and let f

Given, A = {6, 10, 11, 15, 12}

$f: A \rightarrow N: f(n)$ is the highest prime factor of $n$

(1) When $n=6$, the highest prime factor of 6 is 3 .

Hence, f(6) = 3.

(2) When n = 10, the highest prime factor of 10 is 5.

Hence, f(10) = 5.

(3) When $n=11$, the highest prime factor of 11 is 11 as 11 itself is a prime number. Hence, $f(11)=11$.

(4) When n = 15, the highest prime factor of 15 is 5.

Hence, f(15) = 5.

(5) When $n=12$, the highest prime factor of 12 is 3 .

Hence, f(12) = 3.

Hence range of f is { 3,5,11}