A 100 gallon tank is initially filled with pure water. Brine(salty water)enters containing 0.5 lbs of salt per gallon at a rate of 4 gallons per minute. The mixture is kept thoroughly mixed and drains at a rate of 3 gallons per minute. Let y = y(t) = salt amount(lbs) at time t(minutes). = Then y' = rate in â rate out. y = 2 Which differential equation models the change in salt content at time t? 3 y(0) = 0 100 +t 3 Oy' y(0) = 100 +t 3 O y' + y(0) = 0 100 - t · y = 2 = 0 .y = 2 3 Oy' y = 2 y(0) = = 0 100 -t 3 y' + 100 y = 2 y(0) = 0 oo Part 2 of 2 The correct differential equation is 3 y' + 100 +t .y = 2, y(0) = 0. Solving this differential equation yields the equation for the salt amount at time t. y(t) 0.5(100 + t) â 0.5 · 1004(100 +t) - 3. Use the solution to determine the concentration of salt after t = 40 minutes.