To simplify the expression \(\frac{5}{3 \sqrt{5}}\), we need to rationalize the denominator. To do this, we multiply the numerator and the denominator by \(\sqrt{5}\):
\[ \frac{5}{3 \sqrt{5}} \cdot \frac{\sqrt{5}}{\sqrt{5}} = \frac{5 \sqrt{5}}{3 \cdot 5} = \frac{5 \sqrt{5}}{15} \]
Now, we can simplify \(\frac{5 \sqrt{5}}{15}\):
\[ = \frac{\sqrt{5}}{3} \]
So, the exact simplified answer is:
\[ \frac{\sqrt{5}}{3} \]