Pure water flows into a mixing tank of volume V = 300 m3 at the constant volume rate of 10 m3/s. A solution with a salt concentration of si, kg/m3 flows into the tank at a constant volume rate of 2 m3/s. Assume that the solution in the tank is well mixed so that the salt concentration in the tank is uniform. Assume also that the salt dissolves completely so that the volume of the mixture remains the same. The salt concentration so kg/m3 in the outflow is the same as the concentration in the tank. The input is the concentration si,(t). Whose value may change during the process, thus changing the value of so obtain a dynamic model of the concentration s".