4 Data Analysis 34A random sample of golf scores gives the following summary statistics:n = 20, x = 84.5, Sx = 11.5, minX = 68, Q1 = 78,Med = 86, Q3 = 91, maxX = 112.What can be said about the number of outliers?A B. 1 C. 2 D. At least 1E. At least 2
6 Data Analysis 35 Which of the following statements are true? I. Two students working with the same set of data may come up with histograms that look different.II. Displaying outliers is less problematic when using histograms than when using stemplots.III. Histograms are more widely used than stemplots or dotplots because histograms display the values of individual observations.A. I only B. II only C. III only D. I and II E. II and III
11 Data Analysis 37A simple random sample of 25 world-ranked tennis players provides the following statistics:number of hours of practice per day x-bar = 7.3, sx = 1.2,yearly winnings y-bar = $1,820,000, sy = $310,000, Correlation r = 0.23.Based on this data, what is the resulting linear regression equation?A. Winnings = 1,390, ,400 hoursB. Winnings = 1,300, ,300 hoursC. Winnings = -63, ,000 hoursD. Winnings = -443, ,000 hoursE. Winnings = -10,000, ,620,000 hours
16 Data Analysis 39Using the most commonly accepted definition of outliers, a set has five outliers. If every value of the set is increased by 20%, how many outliers will there now be? A. Fewer than 5 B. 5 C. 6 D. More than 6 E. It is impossible to determine without further information.
18 Data Analysis 40Which of the following statements about the correlation r are true?I. When r = 0, there is no relationship between the variables.II. When r = 0.2, 20% of the variables are closely related.III. When r = 1, there is a perfect cause-and-effect relationship between the variables.A. I only B. II only C. III only D. I, II, and III E. All the statements are false.
23 Data Analysis 42Suppose a study finds that the correlation coefficient relating job satisfaction to salary is r = +1.Which of the following are proper conclusions?I. High salary causes high job satisfaction.II. Low salary causes low job satisfaction.III. There is a very strong association between salary and job satisfaction.A. I only B. II only C. III only D. I and II E. I, II, and III
28 Data Analysis 44When a set of data has suspect outliers, which of the following are preferred measures of central tendency and of variability? A. Mean and standard deviation B. Mean and variance C. Mean and range D. Median and range E. Median and interquartile range
30 Data Analysis 45Which of the following statements are true? I. The range of the sample data set can never be greater than the range of the population. II. While the range is affected by outliers, the interquartile range is not. III. Changing the order from ascending to descending changes the sign of the range. A. I only B. II only C. III only D. I and II E. I and III
34 Data Analysis 47A scatterplot of a company’s revenues versus time indicates a possible exponential relationship. A linear regression on y = log(revenue in $1,000) against x = years since 2005 gives ŷ = x with r = Which of the following are valid conclusions (on next slide)?
35 I. On the average, revenue goes up 0. 63 thousand dollars per year. II I. On the average, revenue goes up 0.63 thousand dollars per year. II. The predicted revenue for year 2009 is approximately 1,862 thousand dollars. III. 46% of the variation in revenue can be explained by variation in time. A. I only B. II only C. III only D. I and III E. None of the above are valid conclusions.
40 Data Analysis 49An AP Statistics teacher started using z-scores. On the second major exam of the marking period, a student receives a grade with a z-score of What is the correct interpretation of the grade? A. The student’s grade went down 1.3 points from the first exam. B. The student’s grade went down 1.3 points more than the average grade went down from the first exam. C. The student scored 1.3 standard deviations lower on the second exam than on the first. D. The student scored 1.3 standard deviations lower on the second exam than the class average on the first exam. E. The student scored 1.3 standard deviations lower on the second exam than the class average on the second exam.
42 Data Analysis 50Given two independent random variables, X with mean 12.3 and standard deviation 0.5, and Y with mean 9.1 and standard deviation 0.3, which of the following is a true statement? A. The mean of X – Y is 21.4 B. The median of X – Y is 3.2 C. The range of X – Y is 21.4 D. The standard deviation of X – Y is 0.8 E. The variance of X – Y is 0.34
44 Data Analysis 51Consider the following total sales histogram. Which of the following are true statements?
45 I. Each year since 1999 the total sales has increased. II. Labeling has resulted in a misleading picture.III. It is possible that the total sales per year decreased every year between 1999 and 2007.A. I only B. II only C. III only D. I and IIE. None of the above gives the complete set of true responses.
47 Data Analysis 52A study of weekly hours of television watched and SAT scores reports a correlation of r = From this information, we can conclude that: A. Students who watch more TV tend to have lower SAT scores. B. The fewer the hours in front of a TV, the higher a student’s SAT score. C. There is little relationship between weekly hours of TV watched and SAT scores. D. There is a strong negative association between weekly hours of TV watched and SAT scores, but it would be wrong to conclude causation. E. A mistake in arithmetic has been made.