Question 1016869
The sum of squares(SS) is defined as the sum of (x - mean)^2 of all x
:
In our example the mean is (3 + 1 + 1 + 1) / 4 = 1.5
:
SS = (3 - 1.5)^2 + (1-1.5)^2 + (1-1.5)^2 + (1-1.5)^2 = 3
:
variance = SS / (n-1) = 3 / 3  = 1 where n = 4
:
std dev = square root(variance) = 1
: