If the marks obtained by the $20$ students are $6, 4, 9, 5, 9, 3, 7, 7, 5, 6, 9, 4, 10, 10, 4, 3, 6, 7, 9, 9$,then the mode of this data is .............

Observations of a data are $28, 16, 9, 17, 82, 71, 41, 18, 25, 15$. Find the range of the data.

The mean of $25$ observations is $36$. If the mean of the first $13$ observations is $32$ and the mean of the last $13$ observations is $40$,find the $13^{\text{th}}$ observation.

If the mean of $20$ observations is $27.2$,then $\Sigma f_{i} x_{i}$ is ............

The facts or figures,which are numerical or otherwise,collected with a definite purpose are called .......

The median of the following observations arranged in ascending order is $53 :$ $41, 48, x+1, x+5, 62, 72$. Find $x$.