4.20 The paper “Caffeinated Energy Drinks—A Growing Problem” (Drug and Alcohol Dependence [2009]: 1–10)

gave the accompanying data on caffeine per ounce for eight top-selling energy drinks and for 11 highcaffeine energy drinks:

Top-Selling Energy Drinks 9.6 10.0 10.0 9.0 10.9 8.9 9.5 9.1 High-Caffeine Energy Drinks 21.0 25.0 15.0 21.5 35.7 15.0 33.3 11.9 16.3 31.3 30.0 The mean caffeine per ounce is clearly higher for the high-caffeine energy drinks, but which of the two groups of energy drinks (top-selling or high-caffeine)

is the most variable with respect to caffeine per ounce? Justify your choice.