1. **State the problem:** We need to analyze maternal blood vitamin D levels in two groups of breastfed infants: those with seizures and those without seizures, based on box-and-whisker plots. 2. **Median comparison:** The median is the middle value of a dataset when ordered. - From the plot, the median maternal blood vitamin D level for the "no seizures" group is approximately $35$ ng/mL. - The median for the "seizures" group is approximately $10$ ng/mL. This shows infants with seizures have a much lower median maternal blood vitamin D level. 3. **Interquartile Range (IQR):** IQR is $Q3 - Q1$, representing the middle 50% of data. - For "no seizures": $Q1 \approx 25$, $Q3 \approx 45$, so $IQR = 45 - 25 = 20$ ng/mL. - For "seizures": $Q1 \approx 5$, $Q3 \approx 15$, so $IQR = 15 - 5 = 10$ ng/mL. The "seizures" group has a smaller IQR, indicating less spread in vitamin D levels. 4. **Upper range outlier for "seizures":** Outliers are values beyond $Q3 + 1.5 \times IQR$. Calculate upper fence: $$Q3 + 1.5 \times IQR = 15 + 1.5 \times 10 = 15 + 15 = 30$$ Any value above $30$ ng/mL in the "seizures" group is an upper outlier. 5. **Percentage below 9 ng/mL in "seizures":** - The box plot shows the lower whisker near $0$ and $Q1$ at $5$. - Values below $9$ ng/mL lie between $0$ and $9$. - Since $Q1$ is $5$ and median is $10$, roughly half the data is below median. - The portion below $9$ is slightly less than half of the group. Estimating percentage: - Approximately $40\%$ of infants in the "seizures" group have maternal blood vitamin D levels below $9$ ng/mL. **Final answers:** - Median no seizures: $35$ ng/mL - Median seizures: $10$ ng/mL - IQR no seizures: $20$ ng/mL - IQR seizures: $10$ ng/mL - Upper outlier threshold seizures: above $30$ ng/mL - Percentage below $9$ ng/mL seizures: approximately $40\%$