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Frequency Distribution Steps in Organizing Data Arrange data into an array Decide on number of classes (k) Determine class interval (CI) Prepare tally sheet Frequency Distribution Data set: 81 86 82 76 92 89 87 82 88 83 85 91 77 93 83 98 92 87 87 82 71 88 78 84 89 93 86 99 85 87 73 90 79 89 83 Frequency Distribution Arrange data into an array 71 81 83 87 89 92 73 82 84 87 76 82 85 87 89 93 77 82 85 87 90 98 78 83 86 88 91 99 79 83 86 92 88 Frequency Distribution Decide on number of classes (k) Use Sturges' Rule k = 1 + 3.3 log n k = 1 + 3.3 log n = 1 + 3.3 log 35 = 1 + 3.3 (1.544) = 6.095 ≈6 Frequency Distribution Determine class interval (CI) •Use the formula CI = HV − LV k CI =( HV − LV)/ k = (99 − 71)/ 6 = 28/ 6 ≈5 Frequency Distribution Class Tally Frequency 70-74 II 2 75-79 IIII 4 80-84 IIIII-III 8 85-89 IIIII-IIIII-III 13 90-94 IIIII-I 6 95-99 II 2 Frequency Distribution Here are some test scores from a math class. 65 91 85 76 85 87 79 93 82 75 100 70 88 78 83 59 87 69 89 54 74 89 83 80 94 67 77 92 82 70 94 84 96 98 46 70 90 96 88 72 Frequency Distribution Class Frequency Relative Frequency Percent 41-50 1 1/40 2.5% 51-60 2 2/40 5% 61-70 6 6/40 15% 71-80 8 8/40 20% 81-90 14 14/40 35% 91-100 9 9/40 22.5% Frequency Distribution Class Frequency Cumulative (Less Than) 41-50 1 1 51-60 2 3 61-70 6 9 71-80 8 17 81-90 14 31 91-100 9 40 Frequency Distribution Class Frequency Cumulative (Greater Than) 41-50 1 40 51-60 2 39 61-70 6 37 71-80 8 31 81-90 14 23 91-100 9 9 Frequency Distribution Let’s suppose that you are collecting data on how many hours of sleep college students get each night. After conducting a survey of 30 of your classmates, you are left with the following set of scores: 7, 5, 8, 9, 4, 10, 7, 9, 9, 6, 5, 11, 6, 5, 9, 10, 8, 6, 9, 7, 9, 8, 4, 7, 8, 7, 6, 10, 4, 8