SECTION 2.2 More Graphs and Displays 57 You can also use a dot plot to graph quantitative data. In a dot plot, each data entry is plotted, using a point, above a horizontal axis. Like a stem-and-leaf plot, a dot plot allows you to see how data are distributed, to determine specific data entries, and to identify unusual data entries. Constructing a Dot Plot Use a dot plot to organize the data set in Example 1. Describe any patterns. Number of Text Messages Sent 75 49 104 59 88 123 75 109 68 81 66 80 78 69 55 76 114 98 73 18 42 84 46 52 25 25 26 33 25 20 32 24 43 17 49 27 32 29 29 40 23 33 30 41 35 38 36 54 30 148 SOLUTION So that each data entry is included in the dot plot, the horizontal axis should include numbers between 15 and 150. To represent a data entry, plot a point above the entry’s position on the axis. When an entry is repeated, plot another point above the previous point. Interpretation From the dot plot, you can see that most entries occur between 20 and 80 and only five people sent more than 100 text messages. You can also see that 148 is an unusual data entry. TRY IT YOURSELF 3 Use a dot plot to organize the points scored by the 55 winning teams listed on page 39. Describe any patterns. Answer: Page A36 Technology can be used to construct dot plots. For instance, Minitab and StatCrunch dot plots for the text messaging data are shown below. MINITAB 150 140 130 120 110 100 90 70 60 50 40 30 20 75 65 55 45 35 25 15 80 145 135 125 115 105 95 85 Number of Text Messages Sent STATCRUNCH 150 140 130 120 110 100 90 70 60 50 40 30 20 75 65 55 45 35 25 15 80 145 135 125 115 105 95 85 Number ofText Messages Sent EXAMPLE 3 15 20 25 30 35 40 45 50 115 120 125 130 135 140 145 150 55 60 65 70 75 80 85 90 95 100 105 110 Number of Text Messages Sent For help with the number line and ordering numbers, see Integrated Review at MyLab Statistics
RkJQdWJsaXNoZXIy NjM5ODQ=