<p>NAME:______DATE:______</p><p>Discrete Quiz Chapter 6</p><p>1. An outlier is an individual value that: A) extends the pattern. B) deviates from the pattern. C) determines the strength of the relationship. D) outlines the general form of the data. Ans: B</p><p>2. If two variables are both positive, and tend to be linked so that growth of one variable tends to indicate growth in the other variable, then: A) the variables are positively associated. B) the variables are negatively associated. C) the variables have no association with each other. Ans: A</p><p>3. If a regression line for two variables has a small positive slope, then: A) the variables are positively associated. B) the variables are negatively associated. C) the association of the variables cannot be determined. D) the variables have no association with each other. Ans: A</p><p>4. If two variables are negatively associated, then the regression line: A) has a negative intercept. B) has a negative slope. C) has negative coefficients. D) is valid for only negative values. Ans: B</p><p>5. If the regression line is 2x + 4y = 10, then the variables: A) have a positive association. B) have a negative association. C) have an association that is sometimes positive and sometimes negative. Ans: B</p><p>6. If the variables have a negative association, then their correlation: A) must be less than 1. B) must be between 1 and 0. C) must be between 0 and 1. D) must be greater than 1. Ans: B</p><p>7. If the correlation between two variables is 1, then the points of their scatterplot: A) all lay within 1 unit of the regression line. B) all lay within ½ unit of the regression line. C) all lay on the regression line. D) lay so that exactly half of the points are on each side of the regression line. Ans: C</p><p>8. If the units of measurement change to larger units, then the correlation: A) becomes larger. B) becomes smaller. C) does not change. Ans: C</p><p>9. The intercept of the least-squares regression line is A) the mean of the y values. B) the mean of the x values. C) the mean of the y values minus the mean of the x values. D) none of these. Ans: D</p><p>10. If the least-squares regression line is y = 3x -5, then for y= 2, the predicted value for x is: A) 1. B) 3. C) 2 1/3. D) 6. Ans: C</p><p>11. If the least-squares regression line is y = 5x  3, then for x = 3, the predicted value for y is: A) 2. B) 0. C) 1 1/5. D) 12. Ans: D Use the following scatterplot to answer questions 12-13.</p><p>12. For the scatterplot shown below, what can you say about the least-squares regression line?</p><p>A) Its slope is positive. B) It passes through the point (0,0) C) It stops at y = 800 D) None of these Ans: A</p><p>13. For the scatterplot shown below, what can you say about the correlation?</p><p>A) It is almost 0. B) It is between 0 and 1. C) It is exactly 1. D) It is greater than 1. Ans: B Use the following scatterplot to answer questions 14-15.</p><p>14. What can you say about the slope of the least-squares regression line?</p><p>A) The slope is zero. B) The slope is positive. C) The slope is negative. D) The slope varies. Ans: B</p><p>15. What can you say about the correlation?</p><p>A) The correlation is greater than 1. B) The correlation is exactly 1. C) The correlation is between 0 and 1. D) The correlation is negative. Ans: C</p><p>16. Suppose the points of a scatterplot lie close to the line 3x + 2y = 6. The slope of this line is: A) 3. B) 2/3. C) 3/2. D) 3/2. Ans: D 17. For professional baseball players, one would expect a negative correlation between: A) batting average and salary. B) years of play and salary. C) number of home runs and salary. D) number of errors and salary. Ans: D</p><p>18. A typing service keeps data on the number of pages in a manuscript and the length of time (in hours) it takes to complete the typing. The least squares regression line for the data is given by y = 20 + 0.273x. Use this to predict the length of time needed to type a 40-page manuscript. A) 810.92 B) 60.273 C) 30.92 D) 16.38 Ans: C</p><p>19. A bank collects data on the savings and incomes of families to predict an expected increase in certificate of deposit accounts due to a 10% increase in salaries of employees at a local company. Which variable, savings or income, would be the explanatory variable? A) Family savings B) Family income Ans: B</p><p>20. A university admissions counselor wishes to predict the performance of freshmen by considering their SAT scores. Which variable, freshman GPA or SAT score, would be the explanatory variable in a least squares regression equation? A) Freshman GPA B) SAT score Ans: B</p><p>21. Max is collecting baseball cards. He has 65 that his aunt gave him for his birthday, and he buys 20 more each week. The total number y of cards that Max has after x weeks is given by which of the following equations? A) y = 20 + 65x B) y = 65 + 20x C) y = 20 + x D) y = 85x Ans: B (For number 22 use the data given below)</p><p>22.What is the correlation between the variables?</p><p>A) About 0.99 B) About 0.94 C) About 0.70 D) About 0.50 Ans: B</p><p>Temperature in 70 72 74 75 81 82 degrees F (y) Chirps per 15 15 15 16 17 17 second (x)</p><p>(For number 23 use the data given below)</p><p>Let x = time spent studying and y = test score.</p><p>Time spent 1 2 5 4 6 7 8 5 2 4 3 5 studying (hours) Test score 49 57 80 70 88 91 98 80 57 72 65 82 (percentage)</p><p>23. What is the expected test score if three hours are spent studying?</p><p>A) About 63 B) About 65 C) About 67 D) About 70 Ans: B</p><p>24. If the x and y coordinates of a scatterplot are exchanged, the correlation of the variables: A) remains unchanged. B) changes to its reciprocal. C) changes to its negative reciprocal. D) none of these. Ans: A</p><p>25. If the x and y coordinates of a scatterplot are exchanged, variables which were previously positively associated: A) remain positively associated. B) are now negatively associated. C) are no longer associated. Ans: A</p>