118 CHAPTER 2 Descriptive Statistics In Exercises 21 and 22, determine whether the approximate shape of the distribution in the histogram is symmetric, uniform, skewed left, skewed right, or none of these. 21. 2 4 6 8 10 12 2 6 10 14 18 22 26 30 34 22. 2 4 6 8 10 12 2 6 10141822263034 23. For the histogram in Exercise 21, which is greater, the mean or the median? Explain your reasoning. 24. For the histogram in Exercise 22, which is greater, the mean or the median? Explain your reasoning. Section 2.4 In Exercises 25 and 26, find the range, mean, variance, and standard deviation of the population data set. 25. The mileages (in thousands of miles) for a rental car company’s fleet. 4 2 9 12 15 3 6 8 1 4 14 12 3 3 26. The ages of the Supreme Court justices as of April 7, 2021 (Source: Supreme Court of the United States) 66 56 72 49 82 71 66 60 53 In Exercises 27 and 28, find the range, mean, variance, and standard deviation of the sample data set. 27. Dormitory room charges (in dollars) for one school year for a random sample of four-year universities 5816 6045 5612 6341 6106 7361 6320 6265 7220 7439 5395 6908 5561 5710 5538 6632 28. Salaries (in dollars) of a random sample of teachers 62,222 56,719 50,259 45,120 47,692 45,985 53,489 71,534 In Exercises 29 and 30, use the Empirical Rule. 29. The mean charge for electricity for a sample of households was $110.00 per month, with a standard deviation of $17.50 per month. Between what two values do 95% of the data lie? (Assume the data set has a bell-shaped distribution.) 30. The mean charge for satellite television for a sample of households was $87.50 per month, with a standard deviation of $14.50 per month. Estimate the percent of satellite television charges between $73.00 and $102.00. (Assume the data set has a bell-shaped distribution.) 31. The mean sale per customer for 40 customers at a gas station is $32.00, with a standard deviation of $4.00. Using Chebychev’s Theorem, determine at least how many of the customers spent between $24.00 and $40.00. 32. The mean duration of the 135 space shuttle flights was about 9.9 days, and the standard deviation was about 3.8 days. Using Chebychev’s Theorem, determine at least how many of the flights lasted between 2.3 days and 17.5 days. (Source: NASA)
RkJQdWJsaXNoZXIy NjM5ODQ=