Is the magnitude of an earthquake related to the depth below the surface at which the quake occurs? Let x be the magnitude of an earthquake (on the Richter scale), and let y be the depth (in kilometers) of the quake below the surface at the epicenter. The following is based on information taken from the National Earthquake Information Center of the U.S. Geological Survey. Additional data may be found by visiting the Brase/Brase statistics site at www.cengagebrain.com and finding the link to Earthquakes.

(a) Make a scatter diagram and draw the line you think best fits the data.
(b) Would you say the correlation is low, moderate, or strong? positive or negative?
(c) Use a calculator to verify that ˆ‘x = 24.1, ˆ‘x2 = 85.75, ˆ‘y = 53.5, ˆ‘y2 = 458.31, and ˆ‘xy = 190.18. Compute r. As x increases, do

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x2.94.23345 2.6 3.2 34 3.2 3.4 y 5.0 0.01.2 10.0 93.95.5