As the article clearly mentions Manhattan as the location of the school, it can be deduced that the country is the U.S.

As for the population ratios in the U.S, a short internet search tells me that there are estimated to be 330 million people living in the U.S as of 2020, of whom it is estimated that 46.8 million are african americans and 60 million are hispanic. That comes down to 14.18% and 18.18% respectively.

So given some margin for error, and accounting for other minority groups, only 1 in 3 would be of another skin colour than white in the U.S.