Look at the table given below:

Marks	0-10	11-20	21-30	31-40
No. Of students	6	9	11	4

What is the class size of the class 11-20 in this table?

The given class interval is in the form of inclusive form.

To find out the class size we need to first find out the true class limits.

Now,

By converting the table in exclusive form;

We get,

Class size = True upper limit – True lower limit

Class size = 20.5 – 10.5 = 10