Find the mean deviation about

Given data distribution

Now we have to find the mean deviation about the mean of the distribution Construct a table of the given data

We know that mean,

$\overline{\mathrm{X}}=\frac{\sum \mathrm{f}_{\mathrm{i}} \mathrm{x}_{\mathrm{i}}}{\sum \mathrm{f}_{\mathrm{i}}}=\frac{433}{20}=21.65$

To find mean deviation we have to construct another table

Hence Mean Deviation becomes,

M. $\mathrm{D}=\frac{\sum \mathrm{f}_{\mathrm{i}} \mathrm{d}_{\mathrm{i}}}{\sum \mathrm{f}_{\mathrm{i}}}=\frac{25}{20}=1.25$

Therefore, the mean deviation about the mean of the distribution is 1.25