9. pH Levels in Water A sampling of the acidity of rain for 10 randomly selected rainfalls was recorded at three different locations in the United States, with the pH readings shown in the table.

(note: pH readings range from 0 to 14; 0 is acid, 14 is alkaline. Pure water falling through clean air has a pH reading of 5.7.)

a. Do the data present sufficient evidence to indicate differences in the levels of acidity in rainfalls in the three different locations? Test using the Kruskal–
Wallis H-test.

b. Find the approximate p-value for the test in part a and interpret it.

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Northeast Middle Atlantic Southeast 4.45 4.60 4.55 4.02 4.27 4.31 4.13 4.31 4.84 3.51 3.88 4.67 4.42 4.49 4.28 3.89 4.22 4.95 4.18 4.54 4.72 3.95 4.76 4.63 4.07 4.36 4.36 4.29 4.21 4.47