Atank contains 50 kg of salt and 2000 l of water. a solution of a concentration 0.0125 kg of salt per liter enters a tank at the rate 7 l/min. the solution is mixed and drains from the tank at the same rate.
(a) find the amount of salt in the tank after 3.5 hours.
(amount in kg)
(b) find the concentration of salt in the solution in the tank as time approaches infinity.
(concentration in kg/l)