Present Value with Variable Rates

A savings bond paid an effective rate of interest of $\displaystyle 2\%$ in the first year, $\displaystyle 3\%$ in the second year and $\displaystyle 2.5\%$ in the third year.
After $\displaystyle 3$ years the balance was $\displaystyle \pounds 8000$.
Calculate the amount originally deposited.
Give your answer to the nearest penny.

An account paid an effective rate of interest of $\displaystyle 1.5\%$ per year for $\displaystyle 2$ years and then $\displaystyle 2.2\%$ per year for $\displaystyle 2$ years.
After $\displaystyle 4$ years the balance was $\displaystyle \pounds 5400$.
Calculate the amount originally deposited.
Give your answer to the nearest penny.

An account paid an effective rate of interest of $\displaystyle 0.5\%$ per month for $\displaystyle 6$ months and then $\displaystyle 0.3\%$ per month for $\displaystyle 6$ months.
After $\displaystyle 12$ months the balance was $\displaystyle \pounds 3200$.
Calculate the amount originally deposited.
Give your answer to the nearest penny.

A corporate account paid an effective rate of interest of $\displaystyle 4\%$ in the first year and $\displaystyle 1.8\%$ in the second year.
After $\displaystyle 2$ years the balance was $\displaystyle \pounds 4500$.
Calculate the amount originally deposited.
Give your answer to the nearest penny.