The idea of intelligence Quotient or I.Q. was utilized first of all in 1961in the Stanford Binet tests. I.Q. is the ratio between mental age (MA) and chronological age (CA). the chronological age is determined from the date of birth and the mental age by intelligence tests. For example, if the average score of the children of 13 plus in age turns out to be 75 will be said to have a mental age of 13, whatever be his chronological age. Mental age does not increases with the chronologic age. Having understood the mental age properly, it is easy to understand I.Q. The equation for the calculation of I.Q. is as follows:
I.Q. = MA/CA * 100
As in evident from the above equation to calculate I.Q. the mental age upon the chronological age and then multiplied by 100. To take an example , suppose a four years old child has a mental age of three years. His I.Q. will be calculated with the help of the following equation:
¾*100 = 75.
Actually, the I.Q. reveals the mental ability of the individual on the basis of which he can be directed about his future. I.Q. is the result of both heredity and environment. Thus a chance in environment may change the I.Q.