Final answer:
The correct formula to calculate IQ using chronological age (CA) and mental age (MA) is MA ÷ CA × 100. For instance, if an 8-year-old child has the mental age of a 10-year-old, the IQ is calculated as (10 ÷ 8) × 100 equals 125, which is above average.
Step-by-step explanation:
The formula that uses chronological age (CA) and mental age (MA) to calculate the intelligence quotient (IQ) is:
Option A. MA ÷ CA × 100.
This formula is commonly used historically in psychometrics to measure a person's intelligence level. To explain further, if a person's mental age is equal to their chronological age, their IQ would calculate to 100, which is considered average. An IQ between 85 and 115 is regarded as typical, and scores are often interpreted in the context of the bell curve distribution where a score of 70 or below may indicate an intellectual disability, and a score of 130 or higher might suggest that someone is gifted or has superior intelligence.
For example, if an 8-year-old child has the mental capacity of a 10-year-old, their IQ would be calculated as follows:
IQ = (10 ÷ 8) × 100
IQ = 1.25 × 100
IQ = 125
Thus, the child's IQ score is 125, which is above average.