Amachine coats metal spheres with a plastic coating. the metal spheres have a radius of 9 mm. the spheres formed by the metal and plastic coating have a radius of 12 mm.
how much plastic coating is on each sphere?
use 3.14 to approximate pi and express your final answer in hundredths.

Find the volumes of the two spheres and subtract.

V = 4/3 * pi * r^3

V = 4/3 * 3.14 * 9^3

Simplify exponent:

V = 4/3 * 3.14 * 729

Multiply:

V = 3052.08

V = 4/3 * pi * r^3

V = 4/3 * 3.14 * 12^3

Simplify exponent:

V = 4/3 * 3.14 * 1728

Multiply:

V = 7234.56

Subtract the two volumes:

7234.56 - 3052.08 = 4182.48

The correct answer is $90