1. The problem statement, all variables and given/known data A tank with a capacity of 400 L is full of a mixture of water and chlorine with a concentration of 0.05 g of chlorine/liter. The chlorine concentration is to be reduced by pumping in fresh water at the rate of 4 liters/second. The mixture is kept stirred and pumped out a rate of 10 liters/second. What is the concentration of the chlorine in the tank 15 seconds later? 3. The attempt at a solution Set x = the amount of chlorine in the main tank. Well there isn't any chlorine entering the main tank, so the mixture going in would be 4, and the amount going out would be 4*(x / 400). So my setup is: (dy/dt) = 4 - 4*(x / 400) And I don't really know where to go from there. I don't even know if my setup is correct. I'm still trying to get the intuition of differential equations, lol. Thanks!