Standard deviation

Now typically, we talk about standard deviation more than variance, and it turns out standard deviation is just the square root of the variance. It's just that simple.

So, if I had this variance of 5.04, the standard deviation is 2.24. So you see now why we said that the variance = (σ)². It's because σ itself represents the standard deviation. So, if I take the square root of (σ)², I get sigma. That ends up in this example to be 2.24.