Suppose you perform a scattering experiment in which you fire BBs into a slab of jello in which a layer of randomly distributed but identical marbles are suspended. Of the BBs entering the jello, 90 percent pass cleanly through without scattering off any marbles. If the total target area presented to the incoming projectiles is 200 cm² and there are 25 marbles hidden in the jello, what is the cross-sectional area for scattering for each marble? What is the radius of a typical marble? Describe how such scattering experiments could be used to probe the structure of subatomic particles.