The accountant at Bintong Chen Coal Distributors, Inc., in Newark, Delaware, notes that the demand for coal seems to be tied to an index of weather severity developed by the U.S. Weather Bureau. When weather was extremely cold in the U.S. over the past 5 years (and the index was thus high), coal sales were high. The accountant proposes that one good forecast of next year’s coal demand could be made by developing a regression equation and then consulting the Farmer’s Almanac to see how severe next year’s winter would be. For the data in the following table, derive a least-squares regression and compute the coefficient of correlation of the data. Also compute the standard error of the estimate.

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COAL SALES (IN MILLIONS OF TONS), y WEATHER INDEX, X 4 2 1 1 4 4 6 5 5 3