Question

The Columbus Dispatch conducted a study. Two identical football, one filled with helium and one filled with ordinary air, were used. A casual observer was unable to detect a difference in the two footballs. A novice kicker was used to punt the footballs. A trial consisted of kicking both footballs in a random order. The kicker did not know which football he was kicking. The distance of each punt was recorded, then another trial was conducted. A total of 39 trials were run. Do the data indicate that helium-filled footballs travel farther than air-filled footballs? Give a confidence interval and significance test. (Data: FTBALL)

Helium	Air	Difference
25	25	0
16	23	-7
25	18	7
14	16	-2
23	35	-12
29	15	14
25	26	-1
26	24	2
22	24	-2
26	28	-2
12	25	-13
28	19	9
28	27	1
31	25	6
22	34	-12
29	26	3
23	20	3
26	22	4
35	33	2
24	29	-5
31	31	0
34	27	7
39	22	17
32	29	3
14	28	-14
28	29	-1
30	22	8
27	31	-4
33	25	8
11	20	-9
26	27	-1
32	26	6
30	28	2
29	32	-3
30	28	2
29	25	4
29	31	-2
30	28	2
26	28	-2

Answer 1