What are the standard mean and standard deviation for IQ scores?

What are the standard mean and standard deviation for IQ scores?

• A. Mean 100, SD 15
• B. Mean 90, SD 10
• C. Mean 110, SD 20
• D. Mean 100, SD 5

Answer: (A)

IQ scores are standardized so the average score sits at 100 and the spread of scores is set by a standard deviation of 15. This means the test developers administer the test to a representative group, calculate the distribution, and rescale so 100 is the center and 15 points is one unit of spread. On this scale, about 68% of people score between 85 and 115, and about 95% fall between 70 and 130, making interpretation consistent across tests. The option with a mean of 100 and a standard deviation of 15 matches this convention, while the other values shift either the center or the spread and don’t reflect the standard IQ scaling.

IQ scores are standardized so the average score sits at 100 and the spread of scores is set by a standard deviation of 15. This means the test developers administer the test to a representative group, calculate the distribution, and rescale so 100 is the center and 15 points is one unit of spread. On this scale, about 68% of people score between 85 and 115, and about 95% fall between 70 and 130, making interpretation consistent across tests. The option with a mean of 100 and a standard deviation of 15 matches this convention, while the other values shift either the center or the spread and don’t reflect the standard IQ scaling.