Direct and Inverse Proportion

These are three separate relationships. All variables are positive.

1. \(y\propto x^2\), and \(y=18\) when \(x=3\). Find the equation and \(y\) when \(x=5\).

2. \(V\propto r^3\), and \(V=40\) when \(r=2\). Find the equation and \(V\) when \(r=3\).

3. \(T\propto\sqrt L\), and \(T=6\) when \(L=9\). Find the equation and \(L\) when \(T=10\).