Question

Long-distance runners have contended that moderate exposure to ozone increases lung capacity. To investigate this possibility, a researcher exposed 12 rats to ozone at the rate of 2 parts per million for a period of 30 days. The lung capacity of rats was determined at the beginning of the study and again after the 30 days of ozone exposure. The lung capacities (in mL) are given here:

(a) If we can assume normality, is there sufficient evidence to support the conjecture that ozone exposure increases lung capacity? Use α = 0.01?

Rat #	1	2	3	4	5	6	7	8	9	10	11	12	y-bar	s
Before	8.7	7.9	8.3	8.4	9.2	9.1	8.2	8.1	8.9	8.2	8.9	7.5	8.45	0.52
After	9.4	9.8	9.9	10.3	8.9	8.8	9.8	8.2	9.4	9.9	12.2	9.3	9.66	0.99

(b) Estimate the size of the increase in lung capacity after exposure to ozone. Use a 99% confidence interval.

Answer 1