Question

What is the standard deviation of {1, 1, 1, 3, 3, 3}?

Answer 1

Standard deviation (population): `sigma_("pop.")=1`

Explanation:

The mean is clearly `2`

Each value deviates from the mean by `+-1`
So the square of each value's deviation from the mean is `1`

and the average of the squared deviations (i.e. the variance, `sigma_("pop.")^2`) is 1

Therefore the standard deviation (assuming the data represents the entire population) is `sigma_("pop.") = sqrt(1) = 1`