10.58 Lung capacity revisited Refer to Exercise 10.34 about measuring the lung function (called the forced vital capacity, or FVC, measured in liters) before and after using an inhaler. The data are shown again in the following table.

Checkup 1 2 3 4 5 Before using inhaler: 5.08 5.99 5.32 6.03 5.44 After using inhaler: 5.36 5.98 5.62 6.26 5.68

a. By how much, on average, did the FVC improve after using the inhaler?

b. Find a 95% confidence interval for the mean improvement and interpret.

c. Suppose you wrongly analyzed the data as two independent samples. Find the confidence interval for the difference in the population means and show how the conclusions would change substantially.