What exactly is standard deviation?
Like IQ for example. The standard deviation is 15 points. So if your IQ is 130, you are "2 standard deviations from the norm".
But is there a % formula to calculate percentile? I think there is but I can't remember it. And are these %'s the same for everything?
I seem to remember seeing it was like 69%-95%-99% or something?
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