Means
Definition: Means
Let \(a_1, \dotsc, a_n\) be a list of [[The Real Numbers|real numbers]].
The harmonic mean of \(a_1, \dotsc, a_n\) is
\[ \frac{n}{\frac{1}{a_1} + \cdots + \frac{1}{a_n}} = \frac{n}{\sum_{k = 1}^n \frac{1}{a_k}} \]
The geometric mean of \(a_1, \dotsc, a_n\) is
\[ \sqrt[n]{a_1 \times \cdots \times a_n} \]
The arithmetic mean of \(a_1, \dotsc, a_n\) is
\[ \frac{a_1 + \cdots + a_n}{n} = \frac{1}{n} \sum_{k = 1}^n a_k \]
The root-mean square or quadratic mean of \(a_1, \dotsc, a_n\) is
\[ \sqrt{\frac{a_1^2 + \cdots + a_n^2}{n}} \]