Solution:
Given regular pyramids;
The volume, V, of a regular pyramid is;
[tex]\begin{gathered} V=\frac{1}{3}bh \\ \\ \text{ Where }b=area\text{ of base},h=height \end{gathered}[/tex]
(a)
[tex]\begin{gathered} S_{ABCD}=9cm^2,SO=5cm \\ \\ V=\frac{1}{3}(9)(5)cm^3 \\ \\ V=15cm^3 \end{gathered}[/tex]
(b)
[tex]\begin{gathered} S_{ABCDEF}=500mm^2,SO=3cm \\ \\ S_{ABCDEF}=50cm^2 \\ \\ V=\frac{1}{3}(50)(3)cm^3 \\ \\ V=50cm^3 \end{gathered}[/tex]
