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.

What do you mean by class-frequency? What is relative class-frequency of any class-interval?

What is frequency density of a class-interval? If the class-frequency of the class $19.5-29.5$ be $7$, then what is its frequency density?

The number of babies of each of $50$ families of your locality are given below:

$\begin{array}{ccc}4& & 0\\ 1& & 0\\ 5& & 4\\ 6& & 2\\ 2& & 2\end{array}\begin{array}{cccc}& 1& & 2\\ & 2& & 2\\ & 1& & 1\\ & 2& & 3\\ & 4& & 2\end{array}\begin{array}{cccccc}& 6& & 4& & 2\\ & 4& & 2& & 2\\ & 2& & 2& & 1\\ & 3& & 4& & 1\\ & 2& & 3& & 6\end{array}\begin{array}{cccccc}& 3& & 5& & 4\\ & 4& & 2& & 3\\ & 4& & 3& & 5\\ & 1& & 2& & 1\\ & 1& & 4& & 6\end{array}$

Prepare a grouped frequency distribution of the above raw data taking the class-intervals $0-2, 2-4, 4-6,.......$etc.