The proportion of frequencies lying on either side of the mean in a normal distribution curve within a range of +1 to -1 standard deviation is approximately:
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In a normal distribution, about 68% of the data falls within one standard deviation from the mean.
Step 1: Learn the characteristics of a normal distribution. For a normal distribution, roughly 68% of the data falls within one standard deviation of the mean, encompassing values both greater and lesser. This is a core feature of the bell curve.