3/8:3

To simplify the ratio \( \frac{3}{8} : 3 \), you can convert the ratio to a fraction:

\[ \frac{3/8}{3} = \frac{3}{8} \times \frac{1}{3} = \frac{3}{24} = \frac{1}{8} \]

So, the simplified ratio is \( 1 : 8 \).