For any sort of pyramid or cone, the volume is 1/3 of the volume of a prism with the same base and height. Since the volume of a prism/cylinder is [tex]V=Bh[/tex], the volume of a pyramid/cone is [tex]V=\frac{1}3Bh[/tex].
In this case, our base is a circle, which has a radius of 4 cm.
The area of a circle is [tex]A=\pi r^2[/tex] where r is the radius.
[tex]A=\pi (4)^2=\pi (4\times4)=16\pi=B[/tex]
We now know that our base is 16π cm.
We also know that our height is 9 cm.
Let's plug these into our volume formula.
[tex]V=\frac{1}3\times16\pi \times9[/tex]
Use 3.14 to approximate pi as the question states. 16 × 3.14 = 50.24.
[tex]V\approx\frac{1}3\times50.24\times9[/tex]
We could punch all of that into our calculator to get the same answer, but since 1/3 of 9 is clearly 3, let's just go with that.
[tex]V\approx3\times50.24[/tex]
[tex]\boxed{V\approx150.72\ cm^3}[/tex]
