Decide "variance" and "standard deviation" for the following material: material
I am using the following formula for "variance".
$$ s^2 = \frac{1}{n-1} \left( \sum_{i=1}^n x_i^2 - \frac{1}{n}\left(\sum_{i=1}^n x_2 \right)^2 \right) $$
Where √s^2 = "standard deviation"
12.1*2+12.2*2+12.3*4+12.4+12.5 = 122.7
(12.1*2)^2+(12.2*2)^2+(12.3*4)^2+(12.4)^2+(12.5)^2 = 3911.65
For "variance", s^2, i get:
s^2 = (1/9)*(3911.65-((1/10)*122.7^2) = 267.35
And for "standard deviation":
√s^2 = √267.35 = 16.35
However the correct answer is:
Standard deviation: 0.125
Variance: 0.0157
What am I doing wrong here?
How did you come up with $(12.3*4)^2$?
What you wanted was $4(12.3)^2$ which is not the same as $(12.3*4)^2$