The mean of five numbers is $30$. If one number is excluded,their mean becomes $28$. The excluded number is:

Classifying the observations $0, 3, 2, 5, 7, 8, 10, 12, 5, 6, 6, 4, 14, 18, 20$ of a data,the frequency of class $0-5$ is ........

Find the mean,the median,and the mode of the observations:
$33, 92, 55, 90, 35, 77, 58, 41, 80, 64, 46$

If $\bar{x}_{1}, \bar{x}_{2}, \bar{x}_{3}, \ldots, \bar{x}_{n}$ are the means of $n$ groups with $n_{1}, n_{2}, \ldots, n_{n}$ number of observations respectively,then the combined mean $\bar{x}$ of all the groups taken together is given by:

Find the number of observations,if the sum of some observations is $975$ and their mean is $32.5$.

Let $m$ be the mid-point and $l$ be the upper class limit of a class in a continuous frequency distribution. The lower class limit of the class is: