Human Development Index
1. **State the problem:** Calculate the Human Development Index (HDI) given the Life Expectancy Index (LE) = 85, Mean School Years Index (MSYI) = 91, and Expected School Years Index (ESYI) = 0.94.
2. **Formula:** The HDI is calculated as the geometric mean of the three indices:
$$\text{HDI} = \sqrt[3]{LE \times MSYI \times ESYI}$$
3. **Important notes:**
- Each index should be normalized between 0 and 1 before calculation. Since LE and MSYI are given as percentages or values out of 100, we convert them to decimals.
- LE = 85 means 0.85, MSYI = 91 means 0.91, ESYI is already 0.94.
4. **Calculate:**
$$\text{HDI} = \sqrt[3]{0.85 \times 0.91 \times 0.94}$$
Calculate the product inside the root:
$$0.85 \times 0.91 = 0.7735$$
$$0.7735 \times 0.94 = 0.72649$$
5. **Find the cube root:**
$$\text{HDI} = \sqrt[3]{0.72649}$$
Using a calculator:
$$\text{HDI} \approx 0.90$$
6. **Final answer:**
The Human Development Index (HDI) is approximately **0.90** (rounded to two decimal places).
\boxed{0.90}