Have some stats to support this assertion? You've not only got to support the assertion that it is more likely than not that a school with >=51% black and Hispanic students is going to be a "bad school" (which you've failed to define, but I'll take it to mean "underperforming"), but in addition yo'uve also got to prove that a school with >=51% white or Asian students will be a "good" school, or a school that is performing up to some standard. (Which?).