Question: IQ scores are designed to have a mean of 100 and a standard deviation of 15. IQ testing is one way in which individuals are categorized as having different levesl of mental disabilities; there are four levels of mental retardation between the IQ scores of 0 and 70.

b) People with IQ scores of 50-70 are in the topmost category of IQ scores that qualify as impairment. They are said to have mild mental retardation. They can attain as high as a sixth-grade education and are often self-sufficient. What percentage of people falls in this range?
c) An individual has an IQ score of 66. What is her percentile?