What is the standard deviation of the data set given below?

4, 7, 8, 9, 12

First find the mean (average)

(4+7+8+9+12) / 5=8

Now find the sum of squared differences for the terms ... (the difference between the elements and the mean squared)

(4-8) ^2 + (7-8) ^2 + (8-8) ^2 + (9-8) ^2 + (12-8) ^2=34

Now find the variance, that is the average of the squared differences ...

v=34/5

The standard deviation is the square root of the v

st=2.6