# Arithmetic Mean Formula

Sum of all of the numbers of a group, when divided by the number of items in that list is known as the Arithmetic Mean or Mean of the group. For example, the mean of the numbers 5, 7, 9 is 4 since 5+7+9 = 21 and 21 divided by 3 [there are three numbers] is 7.

\[\LARGE \overline{X}=\frac{\sum_{i=1}^{n}X_{i}}{N}\]

Where, N is total number of observations.

Please note that Average is different than an Arithmetic Mean.

### Solved Examples

**Question 1:**The marks obtained by 6 students in a class test are 20, 22, 24, 26, 28, 30. Find the mean ?

** Solution: **

$\overline{x}$ = $\frac{20 + 22 + 24 + 26 + 28 + 30}{6}$

= 25

= 25