If the mean of $18, 2x, 27, 12, 3x, 5x$ and $21$ is $24,$ then find $x$.

The scores (out of $100$) obtained by $33$ students in a mathematics test are as follows:
$69, 48, 84, 58, 48, 73, 83, 48, 66, 58, 84$
$66, 64, 71, 64, 66, 69, 66, 83, 66, 69, 71$
$81, 71, 73, 69, 66, 66, 64, 58, 64, 69, 69$
Represent this data in the form of a frequency distribution table.

....... is a branch of Mathematics in which the extraction of meaningful information is studied.

Expenditure on education of a country during a five-year period $(2002-2006)$,in crores of rupees,is given below:

Elementary education	$240$
Secondary education	$120$
University education	$190$
Teacher's training	$20$
Social education	$10$
Other educational programmes	$115$
Cultural programmes	$25$
Technical education	$125$

Represent the information above by a bar graph.

The observation which is repeated most often in an ungrouped data is called .......... of the data.

If $\bar{x}$ is the mean of $x_{1}, x_{2}, \ldots, x_{n},$ then for $a \neq 0,$ the mean of $a x_{1}, a x_{2}, \ldots, a x_{n}, \frac{x_{1}}{a}, \frac{x_{2}}{a}, \ldots, \frac{x_{n}}{a}$ is