Problem 1: A well stirred tank originally contains 100 gal of fresh water. Then brine containing 1/4 lb of salt per gallon is poured into the tank at a rate of 2 gal/min, and the mixture is allowed to leave the tank at the same rate. What is the amount of salt, in lbs, in the tank at any instant? Problem 2: A well stirred tank with a capacity of 500 gal originally contains 200 gal of water with 1001bs of salt in solution. Brine containing 11b of salt per gallon is pumped into the tank at a rate of 3 gal/min, while uid is allowed to ow out of the tank at a rate of 2 gal/ min. What is the salt concentration at the instant that the tank overows? What about ten minutes later