The Arithmetic Mean

A measure of average / location / central tendency. For a sample $\mathbf{x} = (x_1, x_2, \ldots, x_n)$, it is defined as follows:

$$\overline{\mathbf{x}} = (x_1 + x_2 + \ldots + x_n)/n$$

Examples

The mean of (1, 2, 3, 4, 5, 6, 273) is 42.
The mean number of animal legs is 3.96.
The mean country population is 34.2 million.
The mean number of Facebook friends is 338.
The mean Earth’s surface temperature is 15°C/59°F.
The mean number of dogs per US household is 1.46.
The mean number of moons of the Solar system planets is 36.