Intelligence Quotient is a relative number comparing an individual’s mental and cognitive abilities to the current average performance of a population. Several types of intelligence tests are used to measure these abilities. The average score in a population is 100 and the standard deviation is 15. Approximately 68% of the population falls within the range of 85-115, while 95% has an IQ between 70 and 130. IQ scores of below 70 are associated with mental retardation, and scores above 130 are considered exceptional.