A closed cylindrical storage container with a volume of 2800 cubic inches. The material for the top and bottom will cost $3 per square inch and the material for the sides will cost $4 per square inch. A) What dimensions of the container would minimize the cost of manufacturing it? B) What would the minimum cost be of the container of the dimensions that were found?

πr^2h = 2800, so h = 2800/(πr^2)

So, the cost function is
c = 2*3πr^2 + 4*2πrh
= 6πr^2 + 22400/r

now just find r when dc/dr=0 and use that.