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. Ninetyfive 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%.)