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 
, the volume of a pyramid/cone is 
.
In this case, our base is a circle, which has a radius of 4 cm.
The area of a circle is
where r is the radius.
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.
Use 3.14 to approximate pi as the question states. 16 × 3.14 = 50.24.
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.
In this case, our base is a circle, which has a radius of 4 cm.
The area of a circle is
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.
Use 3.14 to approximate pi as the question states. 16 × 3.14 = 50.24.
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.