For this case we have that the area is given by: A = (w) * (l) Where, w: width l: long Substituting we have: 66 = (w) * (w + 5) Rewriting w ^ 2 + 5w - 66 = 0 (w + 11) * (w-6) = 0 Using the positive root we have: w = 6 Answer: the width of the frame is: w = 6 cm
Given that a large mixing tank initially holds 400 gallons of water in which 70 pounds of salt have been dissolved. Pure water is pumped into the tank at a rate of 4 gal/min, and when the solution is well stirred, it is then pumped out at the same rate.
Let Q(t) be the quantity of salt at time t.
Q(0) = 70 pounds
Inflow of water = outflow = 4 gal/min
So resulting volume of tank at time t = 400 gallons