SUPPLEMENTARY EXERCISES for ... - WH Freeman

Section 1 9spread for these data. Then calculate the mean and standard deviation from the scores given inIPS Exercise 1.26, page 30.Chapter 2Section 1S2.1 Here are the golf scores of 12 members of a college women’s golf team in two rounds oftournament play. (A golf score is the number of strokes required to complete the course, so thatlow scores are better.)Player 1 2 3 4 5 6 7 8 9 10 11 12Round 1 89 90 87 95 86 81 102 105 83 88 91 79Round 2 94 85 89 89 81 76 107 89 87 91 88 80(a) Make a scatterplot of the data, taking the first-round score as the explanatory variable.(b) Is there an association between the two scores? If so, is it positive or negative? Explainwhy you would expect scores in two rounds of a tournament to have an association like that youobserved.(c) The plot shows one outlier. Circle it. The outlier may occur because a good golfer had anunusually bad round or because a weaker golfer had an unusually good round. Can you tell fromthe data given whether the outlier is from a good player or from a poor player? Explain youranswer.S2.2 Water flowing across farmland washes away soil. Researchers released water across a testbed at different flow rates and measured the amount of soil washed away. The following tablegives the flow (in liters per second) and the weight (in kilograms) of eroded soil. (Data from G.R. Foster, W. R. Ostercamp, and L. J. Lane, “Effect of discharge rate on rill erosion,” paperpresented at the 1982 Winter Meeting of the American Society of Agricultural Engineers.)Flow rate 0.31 0.85 1.26 2.47 3.75Eroded soil 0.82 1.95 2.18 3.01 6.07(a) Plot the data. Which is the explanatory variable?(b) Describe the pattern that you see. Would it be reasonable to describe the overall pattern bya straight line? Is the association positive or negative?S2.3 In 1974, the Franklin National Bank failed. Franklin was one of the 20 largest banks in thenation, and the largest ever to fail. Could Franklin’s weakened condition have been detected inadvance by simple data analysis? The table below gives the total assets (in billions of dollars)and net income (in millions of dollars) for the 20 largest banks in 1973, the year before Franklinfailed. Franklin is bank number 19. (D. E. Booth, Regression Methods and Problem Banks,COMAP, Lexington, Mass., 1986.)