1. Figure 1 Shows a tank that contains 2.0m3 of water at early stage. A solution containing 25 kg/m3 of salt is added into the tank at a rate of 0.02m3/s. The solution is withdrawn from the tank at a rate of 0.01m3/s. Determine the salt concentration (kg/m3) in the tank when the tank contains 4.0m3 of the solution. (Assumption: The tank is well mixed)