FIGURE 7.6 The Normal Curve of Distribution of IQ Scores The distribution of IQ scores on the WAIS-IV in the general population tends to follow a bell-shaped normal curve, with the average score defined as 100. Notice that 68 percent of the scores fall within the “normal” IQ range of 85 to 115. Ninety-five percent of the general population score between 70 and 130, while only one-tenth of 1 percent score lower than 55 or higher than 145. (Because of rounding, percentages add up to more than 100%.)