That's got nothing to do with it. You were citing "white" vs. black statistics in the first place, so the "white" category is whatever it is, and represents some population that outnumbers blacks 8 to 1. You noted that b/w ( black perp, "white" victim ) assaults occurred with 8 times ( 15:2 ) the frequency as w/b, and then said that the "per capita ration" was 64 to 1 because "whites" outnumber blacks 8 to 1. This is false reasoning. As I pointed out, b/w and w/b assaults would be equal in number if "race" were uncorrelated with the likelihood of being a perp or a victim.
Furthermore, the comparison of b/w with w/b actually involves a complex combination of factors. Your figure of 64 to 1 is completely meaningless.