The article "Caffeinated Energy Drinks-A Growing Problem" (Drug and Alcohol Dependence [2009]: 1-10) gave the following data on caffeine concentration (mg/ounce) for eight top-selling energy drinks:
a. What is the value of the mean caffeine concentration for this set of top-selling energy drinks?
b. Coca-Cola has 2.9 mg/ounce of caffeine and Pepsi Cola has 3.2 mg/ounce of caffeine. Write a sentence explaining how the caffeine concentration of top-selling energy drinks compares to that of these colas.