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 following are the marks (out of $100$) of $60$ students in mathematics:
$16, 13, 5, 80, 86, 7, 51, 48, 24, 56, 70, 19, 61, 17, 16, 36, 34, 42, 34, 35, 72, 55, 75, 31, 52, 28, 72, 97, 74, 45, 62, 68, 86, 35, 85, 36, 81, 75, 55, 26, 95, 31, 7, 78, 92, 62, 52, 56, 15, 63, 25, 36, 54, 44, 47, 27, 72, 17, 4, 30$
Construct a grouped frequency distribution table with a width of $10$ for each class,starting from $0-9$.

The class mark of the class $90-120$ is:

The mean of the $10$ observations is $68$. If each observation is divided by $2$ and then $6$ is added to each result, find the mean of the new observations so obtained.

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 mean of $35$ observations is $42$. Find the sum of those observations $\left(\Sigma f_{i} x_{i}\right)$.