Question

what is the best approximate for the volume of cement used to make one of these spheres?

Answer 1

Since we have that the volume of a sphere is given by:

$V=\frac{3}{4}\pi r^3$

And we have that the diameter equals 3.6ft, we then will have a volume of:

$V=\frac{3}{4}\pi(1.8)^3\Rightarrow V\approx13.74$

Since we have that the volume is approximately 13.74 ft^3, then the best approximation in the problem is A. 13.6 ft^3.