Mental Age and IQ
Originally, the differences between mental age and chronological age were used to compute the intelligence quotient, or IQ. This was computed using the ratio method, with the following formula: mental age/chronological age * 100 = IQ. No matter what the child's chronological age, if the mental age is the same as the chronological age, then the IQ will equal 100.
An IQ of 100 thus indicates a child of average intellectual development. For a gifted child, the mental age is above the chronological age, and the IQ is higher than 140; for an intellectually challenged child, the mental age is below the chronological age, and the IQ is below 70.
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Famous quotes containing the words mental and/or age:
“Hermann Goering, Joachim von Ribbentrop, Albert Speer, Walther Frank, Julius Streicher and Robert Ley did pass under my inspection and interrogation in 1945 but they only proved that National Socialism was a gangster interlude at a rather low order of mental capacity and with a surprisingly high incidence of alcoholism.”
—John Kenneth Galbraith (b. 1908)
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—Lawrence Kutner (20th century)