Chapter Test 521 Chapter Test 9 Take this test as you would take a test in class. 1. Net Sales The equation used to predict the net sales (in millions of dollars) for a fiscal year for a clothing retailer is ny = 23,769 + 9.18x 1 - 8.41x2 where x1 is the number of stores open at the end of the fiscal year and x2 is the average square footage per store. Use the multiple regression equation to predict the y@values for the values of the independent variables. (a) x1 = 1057, x2 = 3698 (b) x1 = 1012, x2 = 3659 (c) x1 = 952, x2 = 3601 (d) x1 = 914, x2 = 3594 For Exercises 2–9, use the data in the table, which shows the average annual salaries (both in thousands of dollars) for librarians and postsecondary library science teachers in the United States for 12 years. (Source: U.S. Bureau of Labor Statistics) Librarians, x Library science teachers, y 55.7 64.3 56.4 67.0 57.0 70.0 57.2 70.8 57.6 73.3 58.1 72.4 58.9 73.0 59.9 72.3 60.8 73.7 61.5 75.5 61.9 77.2 63.6 77.6 2. Construct a scatter plot for the data. Do the data appear to have a positive linear correlation, a negative linear correlation, or no linear correlation? Explain. 3. Calculate the correlation coefficient r and interpret the result. 4. Test the significance of the correlation coefficient r that you found in Exercise 3. Use a = 0.01. 5. Find the equation of the regression line for the data. Draw the regression line on the scatter plot that you constructed in Exercise 2. 6. Use the regression equation that you found in Exercise 5 to predict the average annual salary of postsecondary library science teachers when the average annual salary of librarians is $61,000. 7. Find the coefficient of determination r2 and interpret the result. 8. Find the standard error of estimate se and interpret the result. 9. Construct a 99% prediction interval for the average annual salary of postsecondary library science teachers when the average annual salary of librarians is $61,000. Interpret the results.
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