We make the following table and add other columns after calculations.

The class interval containing or 25^th item is 20-30. Therefore, 20-30 is the median class.

Now, we know that

Median

Here, l = 20, C = 14, f = 14, h = 10 and N = 50

Therefore, Median

So, we can calculate the absolute values of the deviations from the median, i.e., |x_i – Med.|, as shown in the table.

Therefore, we have

And

Hence, the mean deviation about the median for the given data is 10.34.