The mean marks (out of $100$) of boys and girls in an examination are $70$ and $73$,respectively. If the mean marks of all the students in that examination is $71$,find the ratio of the number of boys to the number of girls.

The mean of $3, -3, -3, 3, 3, -3$ is ..........

Draw a frequency polygon for the following frequency distribution:

Class	$20-30$	$30-40$	$40-50$	$50-60$	$60-70$	$70-80$
Frequency	$5$	$7$	$12$	$7$	$10$	$9$

$A$ football player scored the following number of goals in $10$ matches:
$1, 3, 2, 5, 8, 6, 1, 4, 7, 9$
Since the number of matches is $10$ (an even number),the median is calculated as:
Median $= \frac{5^{\text{th}} \text{ observation} + 6^{\text{th}} \text{ observation}}{2}$
$= \frac{8 + 6}{2} = 7$
Is this the correct answer? If not,why?

Three coins were tossed $30$ times simultaneously. Each time the number of heads occurring was noted down as follows:
$0, 1, 2, 2, 1, 2, 3, 1, 3, 0,$
$1, 3, 1, 1, 2, 2, 0, 1, 2, 1,$
$3, 0, 0, 1, 1, 2, 3, 2, 2, 0$
Prepare a frequency distribution table for the data given above.

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