Calculating interest rate:

PV Years Int. Rate Future Value
$242 2 ? $307
410 9 896
51,700 15 162,181
18,750 30 483,500

For a given single Future value, Present value, and number of years, the annually-compounded rate is given in decimal form by

\left( \frac{F}{P} \right)^{1/y} \ -\ 1