A tank with the capacity of 500 gal originally haves 200 gal of water with 100 lb of salt in solution. Water containing 1 lb of salt per gallon is entering at the rate of 3 gal/min, and the mixture is allowed to to flow out of tank at a rate of 2 gal/min. Determine the amount of salt in the tank at any time prior to the instant when solution begins to overflow. Compute the concentration (in pounds per gallon) of salt in tank when it is at the point of overflow. Compare this concentration with theoretical concentration if the tank had infinite capacity.