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").
... in the town is $60,209, and the median income for a family is $67,375. Males have a median income of $50,715 versus $34,301 for females. The per capita income for the town ...