# Mean

For a data set, the arithmetic mean, also known as "arithmetic average", is a measure of central tendency of a finite set of numbers: specifically, the sum of the values divided by the number of values. The arithmetic mean of a set of numbers x1, x2, ..., xn is typically denoted using an overhead bar, ${\displaystyle {\bar {x}}}$.[note 1] If the data set were based on a series of observations obtained by sampling from a statistical population, the arithmetic mean is the sample mean (${\displaystyle {\bar {x}}}$) to distinguish it from the mean, or expected value, of the underlying distribution, the population mean (denoted ${\displaystyle \mu }$ or ${\displaystyle \mu _{x}}$[note 2]).[1]