To approximate R calculate the proportion change (take 1 minus your answer to (a) divided by your answer to (b)) BMI and the variability of BMI values across the entire sample of 311 observations. The mean BMI of -0.97 indicates the average position relative to a reference point (which is not specified but typically would be a zero point or a population mean), and the standard deviation of 2.18 indicates that the BMI values typically vary by 2.18 units from the mean in