Step 1: Concept Identification: The query seeks the initial formula for calculating the Intelligence Quotient (IQ), commonly known as the ratio IQ.
Step 2: Formula Definition: The IQ concept was introduced by William Stern and later incorporated by Lewis Terman into the Stanford-Binet Intelligence Scale. The formula quantifies a person's intelligence relative to their chronological age. The formula is:
\[ \text{IQ} = \frac{\text{Mental Age (MA)}}{\text{Chronological Age (CA)}} \times 100 \]
Multiplying by 100 standardizes the IQ as a whole number, with 100 representing the average.
Step 3: Explanation of Components:
(A) (Mental Age/Chronological Age) × 100: This accurately represents the formula. For example, a 10-year-old (CA=10) with the mental capabilities of a 12-year-old (MA=12) would have an IQ of (12/10) * 100 = 120.
(B) (Chronological Age/Mental Age) × 100: This is an inversion of the correct ratio.
(C) and (D) are incorrect due to the inclusion of an arbitrary factor of 2.
Step 4: Conclusion: The correct formula for IQ is (Mental Age/Chronological Age) × 100.