Question

If the diameter of the red marble is 3.0 cm, and by using the formula for volume, what is a good approximation of its volume?

Answer 1

You can solve for volume using radius or diameter.
Sphere Volume   =   4/3 • π • r³     =     ( π •d³)/6
We're given the diameter so let's use that.
Volume = PI * d^3 / 6

Volume = 3.14159 * 3.0^3 / 6

Volume = 3.14159 * 9 / 2

Volume = 14.137 cubic centimeters