1. **Stating the problem:** We want to calculate the dependency ratio, which measures the proportion of dependents (young and old) to the working-age population. 2. **Formula:** The dependency ratio is given by: $$\text{Dependency Ratio} = \frac{\text{Population aged 0-14} + \text{Population aged 65+}}{\text{Population aged 15-64}} \times 100$$ 3. **Explanation:** - The numerator is the total number of dependents: children (0-14 years) plus elderly (65 years and older). - The denominator is the working-age population (15-64 years). - Multiplying by 100 converts the ratio into a percentage. 4. **Example:** Suppose a country has 30 million children, 20 million elderly, and 100 million working-age adults. 5. **Calculation:** $$\text{Dependency Ratio} = \frac{30 + 20}{100} \times 100 = \frac{50}{100} \times 100 = 50\%$$ 6. **Interpretation:** A dependency ratio of 50% means there are 50 dependents for every 100 working-age people. This ratio helps understand the economic burden on the productive population.