I think the book mixed up the formulas for the surface area of a sphere and for its volume.

*Try this*"c" has: S=4*π(*r^{2}), to be solved for r. This is the Surface formula. The solution in the back of the book makes no sense: r equals the square root of 3S over 4*π*. But things get more clear when one checks the Solution Key manual, which says r equals the third root of 3S over 4π, which would be the solution if the initial formula given had been the volume formula, V=4/3*π*(r^{3}). So that's why I said there is confusion here with S and V.
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