A tank originally contains 160 gal of fresh water. Then water containing 1/4 lb of salt per gallon is poured into the tank at a rate of 4 gal/min, and the mixture is allowed to leave at the same rate. After 11 min the process is stopped, and fresh water is poured into the tank at a rate of 4 gal/min, with the mixture again leaving at the same rate. Find the amount of salt Q(11) in the tank at the end of an additional 11 min. Round your answer and intermediate answer to two decimal places.