## Harmonic Mean for ungrouped data

Let $x_1, x_2, \cdots , x_n$ be $n$ observations on a variable $X$. Then the Harmonic Mean of these $n$ observations is denoted by $HM$.

## Formula

The harmonic mean for ungrouped data is given by

### $\dfrac{1}{HM} = \dfrac{1}{n}\sum_{i=1}^{n} \dfrac{1}{x_i}$

OR

$$\begin{equation*} HM = \dfrac{n}{\sum_{i=1}^{n} \dfrac{1}{x_i}} \end{equation*}$$

Harmonic mean is undefined if any one value of the variable is zero.