## 1) Given a tank initially contains 200 gallons of brine (salt mixed with water) in which…

1) Given a tank initially contains 200 gallons of brine (salt

mixed with water) in which 150 lbs of salt is dissolved. A salt

solution consisting of 0.5×(1 + e^(-0.02t)) lb. of salt per gallon

(where t is time in unit of minute) is flowing into the tank at a

rate of 10 gal./min and the mixed solution is drained from tank at

the same rate. Find the amount of the salt in the tank after 1

hour. (10 points) (Check “Modified mixing problem on page 14 of the

textbook” under non-narrated Lecture 4 and examples)