Mean

The mean is a value that represents the central or typical value of a collection of numbers, most often referring to the arithmetic mean: the sum of a set of values divided by how many values there are. Mathematicians also study other means, including the geometric mean, the nth root of the product of n values, and the harmonic mean, the reciprocal of the average of reciprocals, which is used for rates and ratios such as average speed over a fixed distance. For nonnegative real numbers the arithmetic mean is always greater than or equal to the geometric mean, which is in turn greater than or equal to the harmonic mean, with equality only when every value in the set is identical. The mean is one of several measures of central tendency alongside the median, the middle value of an ordered set, and the mode, the most frequently occurring value.