IQ is an approximate measure of learning ability. For a 12-year-old, it is expressed relative to all other 12-year-olds. An IQ of 100 is average. About two-thirds of 12-year-olds have an IQ between 85 and 115. Any 12-year-old with an IQ greater than 115, has displayed a learning capacity that is greater than about 84% of all 12-year-olds. Any 12-year-old with an IQ below 85 probably has learning difficulties. Since an IQ approximates learning ability in subjects like language and mathematics, it is relatively stable among those at age 12 and not easily changed in a significant way (though changes are possible). A person who wants to become a mathematician or theoretical physicist, “should” have an IQ greater than 130. For most professions, an IQ of at least 115 might be sufficient. For most skilled jobs, an IQ of 100 is sufficient. However, these are rough approximations because IQ tests are subject to error and other personality factors often compensate for limits in the capacity for abstraction. A person with drive and ambition can often achieve more than an IQ might predict.
