Changing maps using an area ratio

A lake of actual area \(1\text{ km}^2\) is represented by \(6.25\text{ cm}^2\) on a map of scale \(1:n\).

1. Find \(n\). A new map represents the lake by one quarter of its original map area.[2]
2. Find the actual distance represented by \(10\) cm on the new map.[2]