inflection points of a normal curve occur at +/- 1 SD away from the mean.
If you apply the 68/95/99.5 rule, we know the inflection point occurs at 34%, which is after the 30% mark, meaning the curve is bulging upwards at 30%.
450 is half-way between the two y-values, while 30% is half-way between the two x-values. The curvature is exaggerated for emphasis:
k<30, so B
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