7. make a scatterplot to investigate the association between the amount of fluoride in domestic water (ppm) and the number of dental caries in permanent teeth per 100 children for 21 cities.

The data are below.

a. Create the scatterplot

b. Describe the association you see in your scatterplot.

c. The value of r is -0.86, -0.36, 0.36, or 0.86?

CityID FLUORIDE (ppm) CARIES

1 1.9 236

2 2.6 246

3 1.8 252

4 1.2 258

5 1.2 281

6 1.2 303

7 1.3 323

8 0.9 343

9 0.6 412

10 0.5 444

11 0.4 556

12 0.3 652

13 0.0 673

14 0.2 703

15 0.1 706

16 0.0 722

17 0.2 733

18 0.1 772

19 0.0 810

20 0.1 823

21 0.1 1037

Data from Dean, H.T., Arnold, F. A., Jr., & Elvove, E.(1942). Domestic water and dental caries. Public Health Reports, 57, 1155-1179.