# Math Help - Basic Standard Deviation Calculation

1. ## Basic Standard Deviation Calculation

Hi, it's been a while since I've attempted any statistics a just wondering if you could check that I'm using the right method to calculate the standard deviation.

We're given than the mean, $\bar{x} = 8.35$, $\Sigma x = 334$ and $\Sigma x^2 = 3002$ with a sample size of 40.

I used the formula $\sigma =\sqrt{\Sigma (x^2) - \bar{x}^2}$.

Is this the correct formula to use or have I gone wrong somewhere?

Thanks

2. it's $\sigma =\sqrt{\frac{\sum x^2}{n} - \bar{x}^2}$

where n=40

3. Thankyou