This Problem Set is a part of the Lesson 20, Unit 5, Grade 8. A cube's volume is 512 cubic units. What is the length of its edge? If a sphere fits snugly inside this cube, what is its volume? What fraction of the cube is taken up by the sphere? What percentage is this? Explain or show your reasoning. Sphere A has radius 2 cm. Sphere B has radius 4 cm. Calculate the volume of each sphere. The radius of Sphere B is double that of Sphere A. How many times greater is the volume of B?