Who first developed the concept of Intelligence Quotient (IQ)?

→ Who formulated the formula for Intelligence Quotient (IQ)? → Who gave the modern formula for Intelligence Quotient (IQ)? → Who formulated the concept/formula for Intelligence Quotient (IQ)? → What is the significance of 'Chronological Age' in the IQ formula in intelligence testing? → Regarding the historical development of the concept of intelligence measurement and Intelligence Quotient (IQ), from the first intelligence test developed by Alfred Binet in 1905 to the formulation of the IQ formula as the ratio of 'Mental Age' to 'Chronological Age' by William Stern, and finally giving it a modern IQ form by multiplying it by 100 in the Stanford-Binet test by Lewis Terman in 1916; if a child with a chronological age of 8 years has a mental age of 10 years, what will be their IQ according to Terman's modified formula, and under which classification of intellectual ability will this value fall? → Aside from Howard Gardner's theory of multiple intelligences and Robert Sternberg's triarchic theory of intelligence, based on the concept of 'Mental Age' introduced by Alfred Binet and later modified by William Stern and Lewis Terman into the modern formula of 'Intelligence Quotient' (IQ) and its statistical deviation (Standard Deviation): if a 10-year-old child has a chronological age of 12.5 years, and according to the fifth edition of the Stanford-Binet scale (SB5) where the average IQ is set at 100 and the standard deviation (SD) at 15, what would be the child's Deviation IQ or revised IQ score and the correct classification of their intellectual ability?