1. **Stating the problem:** We are given a list of BMI values: 27.9, 26.2, 34.2, 27.9, 16.9, 21.1, 20.7, 24.6, 28.4, 17.9. We want to analyze these values, for example, by calculating the mean (average) BMI. 2. **Formula used:** The mean of a set of numbers is given by $$\text{Mean} = \frac{\text{Sum of all values}}{\text{Number of values}}$$ 3. **Calculate the sum of the BMI values:** $$27.9 + 26.2 + 34.2 + 27.9 + 16.9 + 21.1 + 20.7 + 24.6 + 28.4 + 17.9 = 245.8$$ 4. **Count the number of values:** There are 10 BMI values. 5. **Calculate the mean BMI:** $$\text{Mean} = \frac{245.8}{10}$$ 6. **Simplify the fraction:** $$\frac{\cancel{245.8}}{\cancel{10}} = 24.58$$ 7. **Interpretation:** The average BMI of the given data set is 24.58 kg/m$^2$. This value can be used to understand the general BMI level of the group.