Optimization- Word Problem, minimum amount of material to constuct

A grain silo has the shape of a right circular cylinder surmounted by a hemisphere. If the silo is to have a capacity of http://west.ilrn.com/ilrn/formulaIma...5C%2C3%7D&ns=0, find the radius and height of the silo that requires the least amount of material to construct. http://west.ilrn.com/ilrn/formulaIma...E%7B%5C%2C3%7D

Hint: The volume of the silo is , and the surface area (including the floor) is http://west.ilrn.com/ilrn/formulaIma...Brh%7D%7D&ns=0

... I need to find "r" and "h"