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  ______.

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 

The mean of first  n - natural number is 

The mean of 5 numbers is 18. If one  number  is excluded, their  mean becomes 16, then the excluded number 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

The variance of first  n natural numbers  is

The median of the daily wages of ten   worker in Rs. 20, 25, 17, 18, 8, 15, 22, 11, 9, 14 is 

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

The median of the observations  2, 30, 12, 25, 20, 8, 10, 4, 15, Is

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