At Rachel's 11^th birthday party, 8 girls were timed to see how long (in seconds) they could hold their breath in a relaxed position. After a two-minute rest, they timed themselves while jumping. The girls thought that the mean difference between their jumping and relaxed times would be zero. Test their hypothesis at the 5% level.

Relaxed time (seconds)	Jumping time (seconds)
25	20
46	42
32	29
22	21
23	25
45	43
37	35
29	32