4:16 25

$${\frac{4}{25}} : 16 = {\frac{4}{25}} \cdot {\frac{1}{16}} = {\frac{4}{25 \cdot 16}} = {\frac{4}{25 \cdot 4 \cdot 4}} = {\frac{1}{25 \cdot 4}} = {\frac{1}{100}}$$

Ответ: $$\frac{1}{100}$$