The article Effect of Environmental Factors on Steel Plate Corrosion Under Marine Immersion Conditions (C. Soares, Y.

The article €œEffect of Environmental Factors on Steel Plate Corrosion Under Marine Immersion Conditions€ (C. Soares, Y. Garbatov, and A. Zayed, Corrosion Engineering, Science and Technology, 2011:524€“ 541) describes an experiment in which nine steel specimens were submerged in seawater at various temperatures, and the corrosion rates were measured. The results are presented in the following table (obtained by digitizing a graph).

a. Construct a scatterplot of corrosion (y) versus temperature (x). Verify that a linear model is appropriate.

b. Compute the least-squares line for predicting corrosion from temperature.

c. Two steel specimens whose temperatures differ by 10°Care submerged in seawater. By howmuch would you predict their corrosion rates to differ?

d. Predict the corrosion rate for steel submerged in seawater at a temperature of 20°C.

e. Compute the fitted values.

f. Compute the residuals. Which point has the residual with the largest magnitude?

g. Compute the correlation between temperature and corrosion rate.

h. Compute the regression sum of squares, the error sum of squares, and the total sum of squares.

i. Divide the regression sum of squares by the total sum of squares. What is the relationship between this quantity and the correlation coefficient?

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Corrosion (mm/yr) Temperature (°C) 26.6 1.58 26.0 1.45 27.4 1.13 21.7 0.96 14.9 0.99 11.3 1.05 15.0 0.82 8.7 0.68 0.56 8.2