Question

The ages (in years) of the 6 employees at a particular computer store are 25,38,42,38,30,43. Assuming that these ages constitute an entire population find the standard deviation of the population

Answer 1

first we find the mean (average)
(25 + 38 + 42 + 38 + 30 + 43) / 6 = 216/6 = 36

then subtract the mean (36) from every data point, and square it
25 - 36 = -11...-11^2 = 121
38 - 36 = 2......2^2 = 4
42 - 36 = 6.....6^2 = 36
38 - 36 = 2.....2^2 = 4
30 - 36 = -6...-6^2 = 36
43 - 36 = 7....7^2 = 49

now find the mean (average) of those numbers
(121 + 4 + 36 + 4 + 36 + 49) / 6 = 250/6 = 41.66

to find the standard deviation, we take the square root of that...
sqrt 41.66 = 6.45

so the standard deviation is  6.45 <====