Intelligence Quotient is a Psychological form,that’s an intelligence test.This is an intelligence test score that is obtained by dividing mental age by chronological age and multiplying by 100:a score of 100 thus indicates a performance level at exactly the normal level.
ABBREVIATION: IQ
FORMULA:MA/CA*100.MA= MENTAL AGE
CA= CHRONOLOGICAL AGE
.IQ mainly measure the cognitive abilities of people.At first we should know about intelligence. Intelligence means the ​ability to ​learn, ​understand, and make ​judgments or have ​opinions that are ​based on ​reason in simple.Now the question may be arise in our mind how we’ll know our IQ.That’s the point to know about IQ measurement.At first we should know about them who established this measurement.The concept of IQ was developed by either the German psychologist and philosopher Wilhelm Stern in 1912, or by Lewis Terman in 1916, depending on which sources you consult.Psychologist Alfred BINET was commissioned by the French government to create a testing system to differentiate intellectually normal children from those who were inferior in 1904.
IQ SCALE: 1. Binet Scale (from binet’s IQ Scale work)
2. Simon-Binet Scale
3. Stanford- Binet Scale(1916)

Normal Distribution of IQ Scores:
99.5% OF IQ SCORES – BETWEEN 60 AND 140
95% OF IQ SCORES – BETWEEN 70 AND 130
70% OF IQ SCORES – BETWEEN 85 AND 115
50% OF IQ SCORES – BETWEEN 90 AND 110

The following scale resulted for classifying IQ scores:
Over 140 – Genius or almost genius
120 – 140 – Very superior intelligence
10 – 119 – Superior intelligence
90 – 109 – Average or normal intelligence
80 – 89 – Dullness
70 – 79 – Borderline deficiency in intelligence
Under 70 – Feeble-mindedness

Low IQ & Mental Retardation

50-70 – Mild mental retardation (85%)
35-50 – Moderate mental retardation (10%)
20-35 – Severe mental retardation (4%)
IQ < 20 – Profound mental retardation (1%)
High IQ & Genius IQ

IQ score sometimes fails to measure things such as manual dexterity (obviously), musical talent, and a slew of other abilities that may lead one to many different successes in life. However, a score of an IQ test will give a people’s quiet accurate indication of the ability you possess to think, reason and solve problems which can often be critical in many phases of your life.