The majority of people score within one standard deviation of the mean on an IQ test, which translates into scores ranging from:
A) 75 to 105
B) 89 to 109
C) 85 to 115
D) 80 to 120

Question

Quizplus · Accepted Answer

One standard deviation above and below the mean encompasses about 68% of scores within a normal distribution. For IQ tests, the mean score is typically set at 100 with a standard deviation of 15. Therefore, one standard deviation above and below the mean would be 115 and 85, respectively, resulting in a range of 85 to 115 where the majority (about 68%) of scores fall.

The Majority of People Score Within One Standard Deviation of the Mean