On a aquarium that contains 5L of water of which 2kg of soil has been dissolved completely is to be filled by hose with fresh water at a rate of 2gal/min. The mixture is then stirred and the solution...

Extracted text: On a aquarium that contains 5L of water of which 2kg of soil has been dissolved completely is to be filled by hose with fresh water at a rate of 2gal/min. The mixture is then stirred and the solution being pumped out at the same rate. What is the minimum time before the soil in the aquarium contains less than 0.25kg of soil. How many soil has been pumped out between 10th and 20th minutes?