A 16-year-old male is found to have a mental age of 9 years on I.Q. testing. He has
IQ is (Mental age/ Chronological age) multiplied by 100. Here is it (9/16)* 100 which is 56. IQ is classified as Mild (50-69), Moderate (35-49), Severe (20-34) and Profound (<20). Ref: The ICD-10 Classification of behavioural and mental disorders, CDDG, pg 171.
Mild mental Retardation
Moderate mental retardation
Severe mental retardation
Profound mental retardation
Child psychiatry