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

If the information gathered by an investigator is from an already existing source of data,then such information is called .........

If $\bar{x}$ represents the mean of $n$ observations $x_{1}, x_{2}, \ldots, x_{n},$ then the value of $\sum_{i=1}^{n}(x_{i}-\bar{x})$ is

The blood groups of $30$ students are recorded as follows:
$A, B, O, A, AB, O, A, O, B, A, O, B, A, AB, B, A, AB, B$
$A, A, O, A, AB, B, A, O, B, A, B, A$
Prepare a frequency distribution table for the data.

If the mean of the following data is $20.2,$ find the value of $p:$
$\begin{array}{|c|c|c|c|c|c|} \hline x & 10 & 15 & 20 & 25 & 30 \\ \hline f & 6 & 8 & p & 10 & 6 \\ \hline \end{array}$

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.