20. Meteorology On May 3, 1999, 59 tornadoes hit Oklahoma in the largest tornado outbreak ever recorded in the state. Sixteen of these were classified as strong (F2 or F3) or violent (F4 or F5).
    1. Make a box-and-whisker plot of the data for length of path.
    2. Identify the outliers. Remove them from the data set and make a revised box-and-whisker plot.
    3. Writing How does the removal of the outliers affect the box-and-whisker plot? How does it affect the median of the data set?

For Exercises 21–23, use the set of values below.

1 1 1 1 1 1 2 3 5 8 13 21 34 55 89 89 89 89 89 89

SOURCE: National Oceanic & Atmospheric Administration

21. At what percentile is 1?
22. At what percentile is 34?
23. Error Analysis A student claims that 89 is at the 70th percentile. Explain the student's error.
24. Advertising An electronics store placed an ad in the newspaper showing flat-screen TVs for sale. The ad says “Our flat-screen TVs average $695.” The prices of the flat-screen TVs are $1200, $999, $1499, $895, $695, $1100, $1300, and $695.
    1. Find the mean, median, and mode of the prices.
    2. Which measure is the store using in its ad? Why did they choose it?
    3. As a consumer, which measure would you want to see advertised? Explain your reasoning.
25. Reasoning Which measure better represents a data set with several outliers—the mean or the median? Justify your answer.

26. The table displays the frequency of scores for one Calculus class on the Advanced Placement Calculus exam. The mean of the exam scores is 3.5.

    Score	1	2	3	4	5
    Frequency	1	3	f	12	3

    1. What is the value of f in the table?
    2. What is the mode of all of the exam scores?
    3. What is the median of all of the exam scores?

27. Grades Some teachers use a weighted mean to calculate grades. Each score is assigned a weight based on its importance. To find a weighted mean, multiply each score by its weight and add the results. For example, a student's final chemistry grade is based on four sources: 30% from lab reports, 10% from quizzes, 25% from the midterm exam, and 35% from the final exam. What is the student's weighted mean given the scores shown?

    Lab Reports	82
    Quizzes	95
    Midterm Exam	76
    Final Exam	88

C Challenge

28. Reasoning What effect will adding 10 to every value in a data set have on the mean, median, mode, range, and box-and-whisker plot? What will be the effect if you multiply each value by 10?

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