The weight of the ball m is directly proportional to the cube of the radius, [tex]r^3[/tex]. This means that the ratio between the weight of the ball with radius 3-in and 2-in should be equal to the ratio between the cubes of the two radii:
[tex] \frac{m_3}{m_2}= \frac{(3 in)^3}{(2 in)^3} [/tex]
So we can find the weight of the ball when its radius is 3 inches:
[tex]m_3 = m_2 \frac{(3 in)^3}{(2 in)^3}= (5605.60 p) \frac{3^3}{2^3}=18919 pounds [/tex]
