Question 9(b)
[Maximum number: 5]

\section*{Figure 2

Figure 3
Diagram NOT accurately drawn.
Figure 2 shows a solid right square-based pyramid with height 20 cm.
The volume of the pyramid is .
The pyramid is standing with its square base on a horizontal table.
The pyramid is divided into a smaller right square-based pyramid of height 10 cm and a frustum of the pyramid, as shown in Figure 3, by a horizontal cut.
Calculate the total surface area, in cm to 3 significant figures, of the frustum of the pyramid.