As the air temperature drops, river water becomes supercooled and ice crystals form. Such ice can significantly affect the hydraulics of a river. The article "Laboratory Study of Anchor Ice Growth" (J. of Cold Regions Engr., 2001: 60-66) described an experiment in which ice thickness (mm) was studied as a function of elapsed time (hr) under specified conditions. The following data was read from a graph in the article: n = 33; x = .17, .33, .50, .67,..., 5.50; y = .50, 1.25, 1.50, 2.75, 3.50, 4.75, 5.75, 5.60, 7.00, 8.00, 8.25, 9.50, 10.50, 11.00, 10.75, 12.50, 12.25, 13.25, 15.50, 15.00, 15.25, 16.25, 17.25, 18.00, 18.25, 18.15, 20.25, 19.50, 20.00, 20.50, 20.60, 20.50, 19.80.
a. The r2 value resulting from a least squares fit is .977. Interpret this value and comment on the appropriateness of assuming an approximate linear relationship.
b. The residuals, listed in the same order as the x values, are

Plot the residuals against elapsed time. What does the plot suggest?

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03-0.92 -1.35 -0.78 -0.680 0.21 0.59 0.13 0.45 0.06 0.62 0.94 0.80 -0.14 0.93 0.04 0.36 1.92 0.78 0.35 0.67 1.02 1.09 0.66 -0.0933 -0.10 -0.24-0.43-1.01-1.75-314