This problem models pollution effects in the Great Lakes. We assume pollutants are flowing into a lake at a constant rate of I kg$/$year$,$ and that water is flowing out at a constant rate of F km$3/$year$.$ We also assume that the pollutants are uniformly distributed throughout the lake. If C$($t$)$ denotes the concentration $($in kg$/$km$3)$ of pollutants at time t $($in years$),$ then C$($t$)$ satisfies the differential equation

dCdt

$=$

FV

$$C $+$

IV