What is asked in the problem is simply the volume of the solid rubber ball. The volume of sphere given the diameter may be calculated by,
V = πd^3 / 6
Substituting the given value of diameter,
V = (π x 3³) / 6 = 9π/2 or 14.14
Thus, one needs approximately 14.14 in³ of material.
The symbol they are using is that of a ray so, order matters.
Ray BC is telling you the ray starts at point B like a line segment BUT continues on towards and through point C rather than stopping at it.
Ray CB is telling you just the opposite; the ray starts at point C, continues on towards and through point B.
