The width of each of five continuous classes in a frequency distribution is $5$ and the lower class-limit of the lowest class is $10$. The upper class-limit of the highest class is:

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.

The number of books in different shelves of a library are as follows:
$37, 22, 24, 27, 28, 27, 20, 36, 21, 20,$
$29, 30, 29, 36, 30, 25, 27, 32, 24, 28,$
$34, 20, 25, 28, 30, 20, 35, 25, 27, 31$
Represent the data given above by a grouped frequency distribution table,taking the class intervals as $18-22, 22-26, 26-30, 30-34, 34-38$.

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.

The following observations are arranged in ascending order:
$26, 29, 42, 53, x, x+2, 70, 75, 82, 93$
If the median is $65,$ find the value of $x$.

Find the mean of the observations $15, 22, 18, 27, 31, 21, 14, 36, 25$ and $34$.