A good example of a vague concept is the concept of a heap of sand -- two or three grains of sand is not a heap, but a thousand is. So how many grains of sand does it take to make a heap? There is no clear line. It appears to be paradoxical to ask at what point a heap stops being a heap as grains are removed. This is known as the paradox of the heap or the sorites paradox (from the Greek language word for "heap").
... 0.84% African American, 0.13% Native American, 1.89% Asian, 0.03% Pacific Islander, 0.62% from other races, and 1.04% from two or more races. 3.33% of the population ...