The distribution of IQ in the population is normal, with 68% of scores clustering between 85 and 115, with a mean of 100. An additional 28% of scores fall between 115 and 130 at the upper end and between 70 and 85 at the lower end.

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Quizplus · Accepted Answer

The distribution of IQ scores in the general population is indeed modeled as a normal (bell-shaped) distribution, with about 68% of people scoring within one standard deviation of the mean (which is 100), thus between 85 and 115. The next 28% (14% in each tail beyond the initial 68%) fall within the second standard deviation, which includes scores between 70 and 85 on the lower end and 115 and 130 on the upper end.

The Distribution of IQ in the Population Is Normal, with 68