The class-mark and class-length of a class-interval are $22$ and $10$ respectively. Find its lower and upper class-boundaries.

Find the frequency density of third class-interval of the given frequency distribution.

Find the relative frequency of the second class-interval of the frequency distribution.

The class-mark of a class-interval of a frequency distribution in $m$ and its class-length is $l$. Find its lower and upper class-limits

Determine the third class-interval of the classes $10-19,20-29,.......$ and find its lower and upper class-boundaries.

Define: class-interval.

Define: lower class-limit and upper class-limit.

Define: class-boundary, lower and upper class-boundaries

Define: class-length.