 where formula_91 and formula_85 is an integer representing rank from 1 to N where N is the highest income bracket.So a randomly selected person (or word, website link, or city) from a population (or language, internet, or country) has formula_93 probability of ranking formula_85.The "80-20 law", according to which 20% of all people receive 80% of all income, and 20% of the most affluent 20% receive 80% of that 80%, and so on, holds precisely when the Pareto index is formula_95.