Many countries, especially those in Europe, have significant gold holdings. But, many of these countries also have massive debts. The following data show the total value of gold holdings in billions of U.S. dollars and the debt as a percentage of the gross domestic product for nine countries (Word Press and Trading Economics websites, February 24, 2012).

a. Develop a scatter diagram for the total value of a country's gold holdings ($ billions) as the independent variable.
b. What does the scatter diagram developed in part (a) indicate about the relationship between the two variables? Do there appear to be any outliers and/or influential observations? Explain.
c. Using the entire data set, develop the estimated regression equation that can be used to predict the debt of a country given the total value of its gold holdings.
d. Use residual analysis to determine whether any outliers or influential observations are present.
e. Suppose that after looking at the scatter diagram in part (a) that you were able to visually identify what appears to be an influential observation. Drop this observation from the data set and fit an estimated regression equation to the remaining data. Compare the estimated slope for the new estimated regression equation to the estimated slope obtained in part (c). Does this approach confirm the conclusion you reached in part (d)? Explain.

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Gold Value ($ billions) Debt (% of GDP) Country 5 81.7 83.2 69.2 119.0 63.7 9.9 55.0 93.2 146 203 France Germany Indonesia Italy Netherlands 147 36 50 United States 487