A solid cylindrical rod of radius 4 cm and length 30 cm together with a solid hemisphere of radius 6 cm are melted. During the melting, 10\% of the material is lost. The remaining molten material is cast into a single solid cube. What is the approximate length of an edge of this cube?
a) 9cm
b) 12.5cm
c) 12cm
d) 11.3cm