Mr. Wilcox's class performed an experiment to investigate whether drinking a caffeinated beverage would increase pulse rates. Twenty students in the class volunteered to take part in the experiment. All of the students measured their initial pulse rates in beats per minute). Then Mr. Wilcox randomly assigned the students into two groups of . Each student in the first group drank 12 ounces of cola with caffeine. Each student in the second group drank 12 ounces of caffeine-free cola. All students then measured their pulse rates again. The table displays the change in pulse rate for the students in both groups. 1. Construct and interpret a 95% confidence interval for the difference in true mean change in pulse rate for subjects like these who drink caffeine versus who drink no caffeine.

2. What does the interval in Question 1 suggest about whether caffeine increases the average pulse rate of subjects like these? Justify your answer