The sum of deviations of a set of observations x₁, x₂, ...., xₙ measured from 50 is −10 and the sum of deviations from 46 is 70, then the number of observations is

The mean and standard deviation of 100 observations are 25 and 9 respectively. If 6 is subtracted from each observation, then mean and standard deviation will respectively be

The sum of all odd numbers from 1 to 41 is :

Mean deviation of a frequency distribution is least when it is measured from

The arithmetic mean of 100 observations is 50. If 10 is added to each observation then what will be the new arithmetic mean?

Mode of the observations 10, 11, 16, 17, 12, 13, 17, 16, 16, 12, 16, 10, 15, 16, 10 is