Question

find the mean of the first twelve natural numbers

Answer 1

Sum of first n natural numbers is n(n+1)/2
so for 12 terms
sum = 12(12+1)/2 = 6×13 = 78

So 78 is the sum of first 12 natural numbers. So mean = sum of observations/ number of observations mean = 78/12 = 6.5 So mean is 6.5

Answer 2

First 12 natural numbers are 1,2,3,4,.....12
Sum = 1+2+3+.....+12
         = 78
Mean = 78/12
          = 6.5