Figure 9.20 is a scatterplot relating y =percentage of people using cell phones and x = per capita gross domestic product (GDP) for some nations listed in the Human Development Report.

(a) Give the approximate x- and y-coordinates for the nation that has the highest (i) cell phone use, (ii) GDP.

(b) The least squares prediction equation is ˆy = −0.13 +

2.62x. For one nation, x = 34.3 and y = 45.1.

Find the predicted cell-phone use and the residual. Interpret the residual.

(c) Is the correlation positive, or negative? Explain what it means for the correlation to have this sign.

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Number of Votes for Buchanan 3500- 3000- 2500- 2000 1500- 1000- 500- 10- 10,000 20,000 30,000 40,000 Number of Votes for Perot