The mean of the $10$ observations is $11$. If one new observation is included,their mean becomes $12$. The included new observation is ........

The mean of $10$ observations is $16.5$. It was later noticed that one observation was taken as $57$ instead of $75$ by mistake. Find the correct mean of the data.

Draw a histogram to represent the following grouped frequency distribution:

Ages (in years)	Number of teachers
$20-24$	$10$
$25-29$	$28$
$30-34$	$32$
$35-39$	$48$
$40-44$	$50$
$45-49$	$35$
$50-54$	$12$

$30$ children were asked about the number of hours they watched $TV$ programmes last week. The results are recorded as under:

Number of hours	$0-5$	$5-10$	$10-15$	$15-20$
Frequency	$8$	$16$	$4$	$2$

Can we say that the number of children who watched $TV$ for $10$ or more hours a week is $22$? Justify your answer.

Find the median of the observation: $62, 67, 82, 71, 75, 77, 63, 91$.

Mean of $50$ observations was found to be $80.4$. But later on,it was discovered that $96$ was misread as $69$ at one place. Find the correct mean.