Resolved: how table came ?

hi, you are not explaining how this table  came.

interval start                      interval end
          -                                                    -          

i understood the logic behind it,that our interval width is 20
do we have to write it and count it manually ? am sure it is not

also how we got frequncy table ? manually i can see it is 2, , , , for 1st row
but which function u have used to get that ?
plz explain ,so that it is easy to understand.
thanks