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$($a$)$ Which ring has more wood in it$?$

The napkin ring created by drilling a hole with the larger radius has more wood in it$.$

The napkin ring created by drilling a hole with the smaller radius has more wood in it$.$

The amount of wood in each napkin ring is the same regardless of the size of the sphere used.

$($b$)$ Use cylindrical shells to compute the volume $V$ of a napkin ring of height $9h$ created by drilling a hole with radius $r$ through the center of a sphere of radius $R$ and express the answer in terms of $h.$

$V=$

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