The number of shares held by a person of various companies are as follows. Find the mean:

This is a grouped frequency distribution.

Notice the data in ‘number of companies’, is small and the class in ‘Number of shares’ have equal intervals. So, we can use direct method for ease of calculation and can rely on the answer for accuracy.

So, create the table again as we need to represent midpoints and frequency. Re-creating the table ensures ease of calculation.

The calculation is done on a table and we can easily extract data from it.

We have,

So now, we have

∑x_if_i = 7000 and ∑f_i = 20

Using direct method,

Mean is given by

⇒ [Using values in the table]

⇒ Mean = 350

Thus, mean is 350.