A person’s chronological age is 20 years, and mental age is 16 years. What would be his IQ?

Correct option is C

To calculate IQ using the traditional formula:
IQ Formula: IQ = (Mental Age / Chronological Age) × 100

Calculation:
Given:

- Mental Age (MA) = 16 years
- Chronological Age (CA) = 20 years
IQ = (16 / 20) × 100
IQ = 0.8 × 100
IQ = 80

Answer: 80

This is the ratio IQ formula, which was used historically (developed by William Stern, popularized by Lewis Terman in the Stanford-Binet test).

However, modern IQ tests (like the WAIS, WISC) use deviation IQ instead, which compares an individual's performance to their age peers using a normal distribution (mean = 100, SD = 15). The ratio method is rarely used today because it doesn't work well for adults (mental age plateaus but chronological age continues).