1. The problem statement, all variables and given/known data Grit, which is spread on roads in winter, is stored in mounds which are the shape of a cone. As grit is added to the top of a mound at 2 cubic meters per minute, the angle between the slant side of the cone and the vertical remains 45º. How fast is the height of the mound increasing when it is half a meter high? 2. Relevant equations V=πr2/3 3. The attempt at a solution So I need to solve for dh/dt. I know dV/dt=2 and I know the height, but not the radius. So I draw a right triangle. Since the angle is 45º, r=h. So r=0.5. Now time to take d/dt of each side. dV/dt=d/dt[πr2/3] 2=1/3πr2*dh/dt I treated r as a constant and h as a function of time here. I applied the product rule and the chain rule. dh/dt=6/πr2 Substitue 0.5 for r and I get dh/dt=24/π The correct answer is 8/π. Where did I go wrong?