and it's volume is
Let b denote the length of the edge of the larger cube then the area of one face is
Then the volume of the larger cube is
Calculate the ration
to #2: Let a, b and c denote the edges of the solid. Then the volume is calculated by
If you increase the edge a of a solid by 5% then you get
Calculate the lenghtes of the 3 edges and determine the new volume. Compare this value with the initial volume.