In Tectonics (Oct. 2004), geologists published their research on the formation of oroclines (curved mountain belts) in the central Appalachian mountains. A comparison was made of two nappes (sheets of rock that have moved over a large horizontal distance), one in Pennsylvania and the other in Maryland. Rock samples at the mountain rim of both locations were collected and the foliation intersection axes (FIA) preserved within large mineral grains was measured for each. The accompanying table shows the number of rock samples in the different FIA measurement categories at the two locations. The geologists tested whether the distribution of FIA trends were the same for the Pennsylvania Nappe and Maryland Nappe using a chi-square test of independence.

a. Give the null and alternative hypothesis for the test.

b. The researchers reported the test statistic as x² = 1.874. Do you agree?

c. Find the rejection region for the test, using α = .05.

d. Make the appropriate conclusion in the words of the problem.

Transcribed Image Text:

OROCLINE Pennsylvania Nappe Maryland Nappe 0-79° 20 FIA 80–149° 17 10 150–179° 10 7