Calculus  Optimization
posted by Nevin .
A cylindrical container with a volume of 3000 cm^3 is constructed from two types of material. The side and bottom of the container cost $0.10/cm^2 and the top of the container costs $0.20/cm^2.
a) Determine the radius and height that will minimize the cost.
b) Determine the ratio of diameter to height.
Could you please help me with these questions please and thank you

Cost=.10*(pi*r^2+2Pi*r*h)+.20PIr^2
volume= PIr^2h or h= volume/PIr^2
h=3000/(PIr^2)
Put that into the cost function for h.
Then take the derivative of cost with respect to r (dCost/dr), set equal to zero, solve for r. 
lol i need help on the same one