Let $A=\{9,10,11,12,13\}$ and let $t: A \rightarrow N$ be defined by $\{(n)=$ the highest prime factor of $n$. Find the range of $f$.
$A=\{9,10,11,12,13\}$
$f: A \rightarrow \mathbf{N}$ is defined as
$f(n)=$ The highest prime factor of $n$
Prime factor of $9=3$
Prime factors of $10=2,5$
Prime factor of $11=11$
Prime factors of $12=2,3$
Prime factor of $13=13$
$\therefore f(9)=$ The highest prime factor of $9=3$
$f(10)=$ The highest prime factor of $10=5$
$f(11)=$ The highest prime factor of $11=11$
$f(12)=$ The highest prime factor of $12=3$
$f(13)=$ The highest prime factor of $13=13$
The range of $f$ is the set of all $f(n)$, where $n \in \mathrm{A}$.
$\therefore$ Range of $f=\{3,5,11,13\}$
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