The mean of first  n - natural number is 

The mean deviation from the observations  3, 8, 12, 19, 20 is

The heights  ( in cm ) of the 15 students of a class are 152, 145, 156,  149, 151, 159, 148, 160,  153, 154, 150, 143, 155,

157, 161 cm.  The median of  height of the student is

Geometric means of 2, 2², 2³, . . . . . 2ⁿ  is 

Find the mean age from the following  data
Age ( Years ) :          20 - 30    30 - 40    40 - 50   50 - 60    60 - 70
Number of person :   3                 5             22          30          2         is 

If in a moderately skewed distribution the value of mode and mean are 6 λ  and 9λ  respectively, then the value of the median is  ______.

The arithmetic mean of n number  of a series is  .  If the sum of first ( n - 1 ) number  is K then the n^th number is

If in a frequency distribution, the mean and median are 21 and 22 respectively, then its mode is approximately?

If 96 is the variance of the scores of a batsman in matches played by him.  Then the standard deviation is

The means  of the series 1, 2, 4, 8, - - - -  2ⁿ is