### Definition

Mean value of set of numbers is sum these numbers devided by amount.

### Usage

Imagine you have 5 customers. Each paid you different amount of money: \1200, $1100, $1150, $900, $1500$.

You can get insight on how much money you make on average from each customer by calculating mean value: (\1200 + $1100 + $1150 + $900 + $1500) / 5 = $1170$

*But some customers bring more money and some less?*
Yes, but they’ll balance each out. Some customers will pay you more then $1170 and some less.

\1200 + $1100 + $1150 + $900 + $1500 = 5 * $1170 = $5850$

The calculating mean value is basically answering the question: I made $5850lastmonth,Ifeachcustomerwouldhavepaidthesameamountofmoneywhatthisamountshouldbetosumupto$5850.

Mean value allows you to ignore *variance* in your data and treat values as equal.
But this can lead to problems in situations when variance cannot. In such situations it might be better to use Median

true man - population mean