Five-year-old Mohan has a mental age of eight years. What is his IQ?

Concept

Ratio IQ compares mental age with chronological age using the formula: IQ = (mental age / chronological age) × 100.

A score of 100 represents equal mental and chronological ages; a score above 100 means mental age is proportionally higher.

Application

1. Let mental age = 8 years and chronological age = 5 years.

2. Substitute the values: IQ = (8 / 5) × 100.

3. Calculate 8 / 5 = 1.6, so IQ = 1.6 × 100 = 160.

Cross-check

Reverse the calculation: mental age = (IQ / 100) × chronological age = (160 / 100) × 5 = 8 years, which matches the given mental age.

Therefore, Mohan’s IQ is 160.