Answer :
V = 4/3 (pi) r^3
ball with radius of 18 cm...
V = 4/3(3.14)(18^3)
V = 4/3(3.14)(5832)
V = 24429.02
ball with radius of 12...
V = 4/3(3.14)(12^3)
V = 4/3(3.14)(1728)
V = 7238.23
24429.02 - 7238.23 = 17190.79 greater <====
ball with radius of 18 cm...
V = 4/3(3.14)(18^3)
V = 4/3(3.14)(5832)
V = 24429.02
ball with radius of 12...
V = 4/3(3.14)(12^3)
V = 4/3(3.14)(1728)
V = 7238.23
24429.02 - 7238.23 = 17190.79 greater <====