IQ stands for “Intelligence Quotient” which is a measure of a person’s intelligence found by means of a test. Before marks 41)                       in such a test can be useful as information about a person, they must be compared with some 42)                      . It is not enough simply to know that a 43)                      of thirteen has scored, say, ninety marks in a particular test. To know whether he is clever, 44)                      , or dull, his marks must be compared with the average achieved by boys of thirteen in that test.
 

In 1906 the psychologist, Alfred Binet (1857-1911), 45)                      the standard in relation to which intelligence has since been 46)                       . Binet was asked to find a method of selecting all children in the schools of Paris who should be put in special classes for certain weaknesses. The problem brought home to him the need for a 47)                       standard of intelligence, and he hit upon the very simple concept of “mental age”.
 

He invented a variety of tests and put large numbers of children of different ages through them. He then 48)                        about the age each test was passed by the average child. For instance, he found that the average child of seven could count backward from 20 to 1. Binet 49)                       the various tests in order of difficulty, and used them as a scale against which he could 50)                       every individual. If, for example, a boy aged twelve could only do tests that were passed by the average boy of nine, Binet held that he was three years below average, and that he had a mental age of nine.

A:  quantified
B:  magnitude
C:  numerical
D:  gained
E:  competent
F:  arrangedG.  juvenileH.  adjacentI.  standardJ.  engageK.  includedL.  concludedM.  averageN.  designedO.  measure