Answer:
D. The distance from the mean to an inflection point
Step-by-step explanation:
We rarely encounter the actual formula for the normal PDF. It is ...
[tex]p(x)=\dfrac{1}{\sqrt{2\pi}}e^{-\dfrac{x^2}{2}}[/tex]
In fact, the inflection points are at x = ±1, where the curve changes from being concave downward to concave upward.
So, one standard deviation is the distance from the mean to an inflection point.
