Great Lakes Problem

Iteration and difference equations are beginning to play a significant role in high school mathematics. The Great Lakes Problem investigates a system of coupled difference equations describing the flow of a pollutant through two of the Great Lakes.
Students at the precalculus level can find solutions using graphing calculators to produce graphs and a table of values. A second approach uses matrix models and matrix multiplication. An analytic solution can be found using geometric series. Finally, the corresponding system of differential equations can be solved using techniques of calculus.