Answer :
Final answer:
Six-year-old Marc with an IQ of 100 has a mental age equal to his chronological age, which is 6. Therefore, The correct option is C) 6.
Explanation:
The formula for calculating IQ is: IQ = mental age ÷ chronological age × 100. Given that Marc's IQ is 100 and his chronological age is 6, we can rearrange the formula to solve for his mental age, leading us to the equation 100 = mental age ÷ 6 × 100. Simplifying this, the mental age equals the chronological age when IQ is 100, meaning Marc's mental age is also 6. Therefore, the answer to the question is C) 6.
