Volume of a cuboid is 1000 cm^3.
Dimensions of cuboid x by x by y.
String is wrapped around the cuboid ( once over the top, bottom and sides forming a cross over on top and bottom, like a package )
Equation of the length of the string is y=ax+(b/x^2)
Use calculus, to find the width (x) of the cuboid that the string length is the minimum, in the form x = a . b ^ (1/3)