what is the standard deviation of the numbers -9, -7, -4, -1, 0, 2, 7, 9, 12

Question

what is the standard deviation of these numbers?

Answer 1

First, we work out the mean: (-9-7-4-1+0+2+7+9+12)/9=1.

Then we subtract the mean from each value:

-10, -8, -5, -2, -1, 1, 6, 8, 11

Then we square these numbers and add the squares:

100+64+25+4+1+1+36+64+121=416 and divide by 9, the data size=416/9=46.22.

This is the variance and the square root is the standard deviation: 6.80 approx.