What is the algebraic sum of deviations of a frequency distribution about its mean?

Quartile deviation for a frequency distribution is

Quartile deviation for a frequency distribution is

The algebraic sum of the deviations from the mean is

Mean Deviation of a Descrete Frequency Distribution

Find the algebraic sum of the deviations of all the observations from their mean.

What is the algebraic sum of the deviations of the values of a variable from their average ? Explain with an example.

Prove that "The Algebraic Sum of deviations from Mean is zero".