2.5 EXERCISES SECTION 2.5 Measures of Position 109 For Extra Help: MyLab Statistics Building Basic Skills and Vocabulary 1. The length of a guest lecturer’s talk represents the third quartile for talks in a guest lecture series. Make an observation about the length of the talk. 2. A motorcycle’s fuel efficiency represents the ninth decile of vehicles in its class. Make an observation about the motorcycle’s fuel efficiency. 3. A student’s grade on the Fundamentals of Engineering exam has a z-score of -0.5. Make an observation about the student’s grade. 4. A student’s IQ score is in the 91st percentile on the Weschler Adult Intelligence Scale. Make an observation about the student’s IQ score. 5. Explain how to identify outliers using the interquartile range. 6. Describe the relationship between quartiles and percentiles. True or False? In Exercises 7–10, determine whether the statement is true or false. If it is false, rewrite it as a true statement. 7. On a box-and-whisker plot, one quarter of a data set lies on the left whisker. 8. The second quartile is the mean of an ordered data set. 9. An outlier is any number above Q3 or below Q1. 10. It is impossible to have a z-score of 0. Using and Interpreting Concepts Finding Quartiles, Interquartile Range, and Outliers In Exercises 11 and 12, (a) find the quartiles, (b) find the interquartile range, and (c) identify any outliers. 11. 56 63 51 60 57 60 60 54 63 59 80 63 60 62 65 12. 22 25 22 24 20 24 19 22 29 21 21 20 23 25 23 23 21 25 23 22 Graphical Analysis In Exercises 13 and 14, use the box-and-whisker plot to identify the five-number summary. 13. 01234567891011 0 10 2 5 8 14. 500 550 600 650 700 500 720 580 605 630 Drawing a Box-and-Whisker Plot In Exercises 15–18, (a) find the five-number summary, and (b) draw a box-and-whisker plot that represents the data set. 15. 39 36 30 27 26 24 28 35 39 60 50 41 35 32 51 16. 171 176 182 150 178 180 173 170 174 178 181 180 17. 4 7 7 5 2 9 7 6 8 5 8 4 1 5 2 8 7 6 6 9 18. 27131289925473754 2 3 5 9 5 6 3 9 3 4 9 8 8 2 3 9 5
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