(a)
\Height of the cylinder is
and inner radius is
.
Thickness is
.
Volume of the cylinder is
.
Apply derivative on each side with respect to
.

Substitute
and
in the above expression.
.
Approximate volume is
.
(b)
\Actual formula for volume is
.
Outside radius of the cylinder is
.
Inner radius of the sphere is
.

Absolute error is difference between actual volume and approximate volume.
\
(a) Approximate volume is
.
(b)
.