Answer: 0.00138

## Explanation **Step 1: Convert percentages to decimals** Returns: 0.21, 0.17, 0.11, 0.18, 0.15 **Step 2: Calculate sample mean** \[ \bar{x} = \frac{0.21 + 0.17 + 0.11 + 0.18 + 0.15}{5} = \frac{0.82}{5} = 0.164 \] **Step 3: Calculate sum of squared deviations** \[ \sum (x_i - \bar{x})^2 = (0.21-0.164)^2 + (0.17-0.164)^2 + (0.11-0.164)^2 + (0.18-0.164)^2 + (0.15-0.164)^2 \] \[ = (0.046)^2 + (0.006)^2 + (-0.054)^2 + (0.016)^2 + (-0.014)^2 \] \[ = 0.002116 + 0.000036 + 0.002916 + 0.000256 + 0.000196 \] \[ = 0.00552 \] **Step 4: Calculate unbiased sample variance** \[ s^2 = \frac{\sum (x_i - \bar{x})^2}{n-1} = \frac{0.00552}{4} = 0.00138 \] Therefore, the correct unbiased sample variance is **0.00138**.

Author: LeetQuiz Editorial Team