I think it's kind of valid for a test to possibly be racist. If your reading word problems and you can closely relate to what's being talked about it's easier to break the problem down into its mathematical components. In the end the problems not any easier, but timewise it'll probably take longer and probably leave more room for someone to make stupid small mistakes. Not saying this test is or not just trying to counter the "lol, tests can't be biased crowd"
It's like if you're chinese and there's a question that involves a tea cup and saucer. It's not central to the problem that you understand what a teacup and saucer are, but you've never seen one before and you're wondering what it is while your doing the long division and percentages that actually encompass the problem. Not something that would directly impact a test, but it'd have indirect implications. It's an added distraction that a british person won't have. It's like if anyone on ATOT went in to take the SATs and they had 50 cent music playing through the whole thing.