NSS 9 5 45 Two tanks each holding 50 L of liquid are interconnected by pipes with liquid flowing from tank A into tank B at a rate of 4 L min and from tank B into tank A at a rate of 1 L min The liquid inside each tank is kept well stirred Pure water flows into tank A at a rate of 3 L min and the solution flows out of tank B at 3 L min If initially tank A contains 2 5 kg of salt and tank B contains no salt only water determine the mass of salt in each tank at time t 0 3 L min Pure water A x 1 50 L x 0 2 5 kg 4 L min 1 L min B x 1 50 L 0 0 kg 3 L min