A silo has cylindrical wall, a flat circular floor, and a hemispherical top. If the cost of construction per square foot is twice as great for the hemispherical top as for the walls and the floor, find the ratio of the total height to the diameter of the base that minimizes the total cost of construction. There was another problem involving the silo which said: for a given volume, find the ratio of the total height to the diameter of the base that minimizes the total surface. For this I wrote the equation for volume and solved for h and then I plugged that into the equation for area of the silo, derived, set equal to zero and found that radius and height both equal cubed route of 3v/5pi which would make the ratio: h+r/2r = 1. What do I have to do differently for this question? Thanks.