Answer:
2:5
Explanation:
Given the ratio:
[tex]400g\colon1\operatorname{kg}[/tex]In order to reduce the ratio, both must be in the same unit.
[tex]\begin{gathered} 1\operatorname{kg}=1000g \\ \implies400g\colon1\operatorname{kg}=400g\colon1000g \end{gathered}[/tex]We can then express it in the simplest form.
[tex]\frac{400}{1000}=\frac{2\times200}{5\times200}=\frac{2}{5}[/tex]The ratio in simplest form is 2:5.
