If sum of the $20$ deviations from the mean is $100$, then find the mean deviation

Q. If the sum of the deviations of all the 35 observations from the average is 150, then find the mean deviation.

Q. If the mean of a observations $x_1,x_2,.....x_{n}is\overline{x},$ then the sum of deviations of observations from mean is

Q. The sum of deviations of 'n' observations from 20 is 20 and sum of deviations same 'n' observations from 30 is - 20 . Find the mean of the observations.

Q. If the algebraic sum of deviations of 20 observations from 30 is 20, then the mean of observations is ___.

Q.

If the sum of the squares of deviations for 10 observations taken from their mean is 2.5, then write thevalue of standard deviation.