Skip Navigation Links
Algebra1: Properties of Arithmetic Mean
To enroll in any of our courses, click here
Properties of Arithmetic Mean
If x1, x2, x3, ..., xn are n values of a variable X, then the arithmetic mean or simply the mean of these values is denoted by and is defined as

Here, the symbol denotes the sum x1, x2, x3, ..., xn.
Or we can say, the arithmetic mean of a set of observations is equal to their sum divided by the total number of observations.
People who saw this lesson also found the
following lessons useful:
Similar Triangle: Proportionality Theorem
Time and Distance
Probability: Favourable Elementry Events
Volume of Cone and Sphere
Sum of n terms of AP
Example The sum of the deviations of a set of n values x1, x2, x3, ..., xn measured from 50 is -10 and the sum of deviations of the values from 46 is 70. Find the values of n and the mean.
Solution We have,

 - 50n = -10
- 46n = 70
  Subtracting equation (ii) from equation (i), we get
- 4n = - 80 => n = 20
Putting n = 20 in equation (i), we get
-50x20 = -10
= 990
Mean = 1/n = 990/20 = 49.5
Hence, n = 20 and mean = 49.5
As many of you know, Winpossible's online courses use a unique teaching method where an instructor explains the concepts in any given area to you in his/her own voice and handwriting, just like you see your teacher explain things to you on a blackboard in your classroom. All our courses include teacher's instruction, practice questions as well as end-of-lesson quizzes for practice. You can enroll in any of our online courses by clicking here.

The format of Winpossible's online courses is also very suitable for teachers who are using an interactive whiteboard such as Smartboard on Promethean in their classrooms, because the course lessons can be easily displayed on such interactive whiteboards. Volume pricing is available for schools interested in our online courses. For more information, please contact us at

 Copyright © Winpossible, 2010 - 2011
Best viewed in 1024x768 & IE 5.0 or later version