Chapter 12.2, Problem 2Q

Mount Etna erupted in 1669, 1780, and 1865 (recall Case Study 8.2.3). When molten lava hardens, it retains the direction of the Earth’s magnetic field. Three blocks of lava were examined from each of these eruptions and the declination of the magnetic field in the block was measured (181). The results are given in the following table. Do these data suggest that the direction of the Earth’s magnetic field shifted over the time period spanned by the eruptions? Let $a=0.05$.

1669	1780	1865
57.8	57.9	52.7
60.2	55.2	53.0
60.3	54.8	49.4

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