The median of the data $78, 56, 22, 34, 45, 54, 39, 54, 84$ is

The mean of the data: $2, 8, 6, 5, 4, 5, 6, 3, 6, 4, 9, 1, 5, 6, 5$ is given to be $5$. Based on this information,is it correct to say that the mean of the data: $10, 12, 10, 2, 18, 8, 12, 6, 12, 10, 8, 10, 12, 16, 4$ is $10$? Give reason.

The mean of $3, -3, -3, 3, 3, -3$ is ..........

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

When the investigator has personally obtained the information for a particular purpose,this data is called ........ data.

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: