How to get the standard deviation

Question

Calculate the population standard deviation of: 1, 2, 3, 4

Round to the nearest hundredth.

Answer 1

mean = 2.5

differences from the mean are -1.5, .5, .5 and 1.5

squared differences are 2.25, .25, .25 and 2.25

sum of squared differences = 5

variance = 5/4 if this is the total population

but var = 5/3 if this is a sample of a larger population

standard deviation = square root of the variance = (1/2)sqr5 = about half of 2.2 = 1.1

or if this is just a sample, then standard deviation = square root of 5/3 = about 2.2/1.732= about 1.3