Question

What is the surface area-to-volume ratio of the spherical barrel cactus

Answer 1

Surface area of a sphere:  A = 4pi*r^2; volume of a sphere:  V = (1/3)*pi*r^3
                                           4*pi*r^2
The desired ratio is A/V = ----------------- = 4(3) / r, where r is the radius of the 
                                           (1/3)*pi*r^3                  sphere.