Consider the experiment described in Exercise 6.7.9. For the same subjects, the change in diastolic blood pressure was 1.1 mm Hg greater, on average, for the subjects on the fruits-and-vegetables diet than for subjects on the standard diet. A 97.5% confidence interval for the difference between the two population means is (-0.3, 2.4). Interpret this confidence interval. That is, explain what the numbers in the interval mean.