SECTION 2.4 Measures of Variation 97 Finding the Sample Mean and Standard Deviation for Grouped Data In Exercises 39 and 40, make a frequency distribution for the data. Then use the table to find the sample mean and the sample standard deviation of the data set. 39. 3 3 5 3 8 0 3 9 6 6 7 1 6 3 2 6 9 1 8 5 0 2 3 4 9 5 8 1 9 7 6 9 6 7 0 6 3 8 6 8 7 3 8 9 3 7 2 4 4 1 40. 1 1 1 0 0 0 0 0 1 0 1 0 0 1 0 1 1 0 0 0 0 1 0 0 1 1 1 0 0 1 1 0 0 0 0 0 1 0 1 1 1 0 0 0 0 1 1 0 0 0 Estimating the Sample Mean and Standard Deviation for Grouped Data In Exercises 41– 44, make a frequency distribution for the data. Then use the table to estimate the sample mean and the sample standard deviation of the data set. 41. College Expenses The distribution of the tuitions, fees, and room and board charges of a random sample of public 4-year degree-granting postsecondary institutions is shown in the pie chart. Use $28,249.50 as the midpoint for “$27,000 or more.” $17,000–$19,499 $22,000–$24,499 $19,500–$21,999 $27,000 or more 6 9 10 11 16 $24,500–$26,999 0–4 hours 10–14 hours 5–9 hours 15–19 hours 25–29 hours 30+ hours 5 5 12 11 24 17 16 20–24 hours FIGURE FOR EXERCISE 41 FIGURE FOR EXERCISE 42 42. Weekly Study Hours The distribution of the number of hours that a random sample of college students study per week is shown in the pie chart. Use 32 as the midpoint for “30+ hours.” 43. Teaching Load The number of courses taught per semester by a random sample of university professors are shown in the histogram. Number of courses taught per semester 5 10 15 20 25 1 2 3 4 Number of professors 16 24 2 18 44. Amounts of Caffeine The amounts of caffeine in a sample of five-ounce servings of brewed coffee are shown in the histogram. Number of 5-ounce servings Caffeine (in milligrams) 5 10 15 20 25 70.5 1 12 25 10 2 92.5 114.5 136.5 158.5
RkJQdWJsaXNoZXIy NjM5ODQ=