I.Q. was originally an acronym for “Intelligence Quotient”
Dr. Terman at Stanford university came up with the idea of putting Mental Age (MA) and Chronological Age (CA), the original products of intelligence testing with the Binet scales, into a ration; this captured the relative stability of intelligence at different ages and dealt with the variable meaning of “equal” differences between MA and CA at different ages.
Today we “build” intelligence tests so they yield a result we label “IQ”; the tasks are scaled so this measure has a mean of 100 and a standard deviation of 15.
Up to approximately 16 years of age you can calculate an approximate “mental age” be substituting values in the original formula:
I.Q. = M.A./C.A. x 100 (to get rid of the decimal point)
M.A. = C.A. x I.Q. / 100
55 = M.A./12 x 100
M.A. = 55 x 12 /100
M.A. = 6.6
our child could do approximately the same as a typical 6 and 1/2 year old youngster
Ask the questions again, this time in this form: “Could the average 6 and a half year old child . . . . ?”