Suppose you make napkin rings by drilling holes with different diameters through two wooden balls (which also have different diameters). You discover that both napkin rings have the same height 3h, as shown in the figure. (Let a = 3.) Use cylindrical shells to compute the volume V of a napkin ring of height 3h created by drilling a hole with radius r through the center of a sphere of radius R and express the answer in terms of h.

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