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Question

What is the length, in units, of the radius of a sphere whose volume and surface area, in cubic units and square units, respectively, are numerically equal?

Accepted Answer

The volume of a sphere is 43 r^3 and the surface area is 4 r^2, so 43 r^3 = 4 r^2.We can divide both sides by 4 r^2, to get 13 r = 1.Therefore, r = 3.