Understanding Pressure - Example 3

Example 3:
Two cubes made of the same material; one has sides twice as the other, lying on a table. Standing on one face, the small cube exerts a pressure M on the table. What is the pressure (in term of M) exerted by the larger cube standing on one of its faces, on the table?

Answer:

For the small cube,

Surface area = x²
Volume = x³
Mass = m
Weight = mg

Pressure,
$$\begin{array}{l}P=\frac{F}{A}\\ P=\frac{mg}{x^2}=M\end{array}$$

For the big cube,
Surface area = 4x²
Volume = 8x³
Mass = 8m (Because the volume is 8 times greater)
Weight = 8mg

Pressure,
$$\begin{array}{l}P=\frac{F}{A}\\ P=\frac{8mg}{4x^2}==2\times \frac{mg}{x^2}=2M\end{array}$$