2. ## Re: Can anyone help?

Show that
$\sigma x^2=\sum \frac{x_i^2}{N}-\sum \frac{x_i}{N}$

Becomes
$\sigma x^2=(\sum \frac{x_i^2}{N})-\mu x$

All sums between i=1 and N

3. ## Re: Can anyone help?

Yup, any help?

4. ## Re: Can anyone help?

That doesn't make any sense because $\sum \frac{x_i}{N}$ is $\mu$

5. ## Re: Can anyone help?

Joyeux
There is something wrong with your formula