Wildlife: Highways The western United States has a number of four-lane interstate highways that cut through long tracts of wilderness. To prevent car accidents with wild animals, the highways are bordered on both sides with 12-foot-high woven wire fences. Although the fences prevent accidents, they also disturb the winter migration patterns of many animals. To compensate for this disturbance, the highways have frequent wilderness underpasses designed for exclusive use by deer, elk, and other animals.

In Colorado, there is a large group of deer that spend their summer months in a region on one side of a highway and survive the winter months in a lower region on the other side. To determine if the highway has disturbed deer migration to the winter feeding area, the following data were gathered on a random sample of 10 wilderness districts in the winter feeding area. Row B represents the average January deer count for a 5-year period before the highway was built, and row A represents the average January deer count for a 5-year period after the highway was built. The highway department claims that the January population has not changed. Test this claim against the claim that the January population has dropped. Use a 5% level of signifi cance.

Units used in the table are hundreds of deer.

Wilderness District 1 2 3 4 5 6 7 8 9 10 B: Before highway 10.3 7.2 12.9 5.8 17.4 9.9 20.5 16.2 18.9 11.6 A: After highway 9.1 8.4 10.0 4.1 4.0 7.1 15.2 8.3 12.2 7.3