Construct the class boundaries of the following frequency distribution table. Also construct less than cumulative and greater than cumulative frequency tables.

Age	$1-3$	$4-6$	$7-9$	$10-12$	$13-15$
Number of children	$10$	$12$	$15$	$13$	$9$

Number of readers in a library are given below. Write the frequency of respective classes. Also write the less than cumulative frequency table.

        If the class-marks of a distribution are $22, 27, 32$, then the width of each class is_____

True lower limit of class $26 - 30$, when the classes are $26 - 30, 31 - 35, 36 - 40 ....$,  is _____.

The marks obtained by $35$ students in a test in statistics (out of $50$) are as below.

$$\begin{gathered} 35 1 15 35 45 23 31 40 21 13 15 \\ 20 47 48 42 34 43 45 33 37 11 13 \\ 27 18 12 37 39 38 16 13 18 5 41 \\ 47 43 \end{gathered}$$

Construct a frequency distribution table with equal class intervals, one of them being $10-20 (20$ is not included).

Who is my friend?

I’ve a friend with me always,

In the nights and through the days.

When I run he runs with me,

Sometimes I lead, sometimes he.

When it’s dark he can’t be seen,

Do you know which friend I mean?

Read the poem carefully and answer the below question.

The letter used more often _____

Lower limit of class $25-30$ is _____.

Given below are the ages of $45$ people in a colony.

$$\begin{gathered} 33 8 7 25 31 26 5 50 25 48 56 \\ 33 28 22 15 62 59 16 14 19 24 35 \\ 26 9 12 46 15 42 63 32 5 22 11 \\ 42 23 52 48 62 10 24 43 51 37 48 \\ 36 \end{gathered}$$

Construct grouped frequency distribution for the given data with $6$ class intervals.

       The range of the data $12, 17, 9, 4, 18, 17, 27, 8$; is _____.

The number of times a variable occurs in a data is called its _____.