Mean, Standard Deviation and variance

Question

I submitted this task, and just got my results. My mean was correct, but standard deviation and variance was wrong.

Could someone explain where i went wrong please? As they have not said.

Answer 1

You have a single deviation smaller than $4$ (in absolute value), and yet your standard deviation is $3.85$? Yes, something's wrong here.

Squares can't be negative. Fix the signs in your last column, and it ought to get better.

Answer 2

Check your last two columns:

You have that $(-4.125)^2 = -17.01$, which is incorrect. Remember that when you square something (or multiply a negative by a negative) you always get a positive. Also, remember to round correctly; $(-4.125)^2 = 17.015625$ which rounds to $17.02$.

Check the rest of your last column for problems like these!

Answer 3

I understand where i went wrong now, and what mistake i made. I have corrected my errors.