## 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.