One normally refers to someone as Puerto Rican due to the fact that the country of Puerto Rico represents their nation of Origin. The last time I checked there is no country in the world we live in called "Black". Puerto Ricans come in all shades, from very fair to very dark. When you refer to someone as black, you're in effect disregarding their country of origin and focusing on their outward appearance only. If I was to use the term white male you wouldn't necessarily think of a country but rather the features that define the physical appearance of that person. So the statement "Aren't most Puerto Ricans at least 10% black?" is a counterfactual analogy and dare I say borders on the imbecellic. Apples and oranges. I don't blame you for this statement as today's media plays a strong part in the perpetuation these type of idealisms and classifications. When I come across statements such as these I take it upon myself to educate others. Cheers.

Acceptable