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Lesson 1.3 %u2022 Displaying Quantitative Data: Dotplots 25DEFINITION DotplotA dotplot shows each data value as a dot above its location on a number line.Figure 1.2 shows a dotplot of the scores on a 20-point quiz for each of the 30 students in a statistics class. You%u2019ll learn how to make and interpret dotplots in this lesson.Quiz score13 14 15 16 17 18 19 20dddddddddddddddddddd ddd dddddd dMaking and Interpreting DotplotsIt is fairly easy to make a dotplot by hand for small sets of quantitative data. For details on making dotplots with technology, see the Tech Corner after the next example.FIGURE 1.2 Dotplot of quiz scores for students in a statistics class.Remember what we said in Lesson 1.2: making a graph is not an end in itself. When you look at a graph, always ask, %u201cWhat do I see?%u201d In Figure 1.2, the dotplot shows that 25/30 0.833 83.3% = = of students in the class earned quiz scores of 16 or higher and that the most common score was a perfect 20.Which cars guzzle gas?Making and interpreting dotplotsPROBLEM: The Environmental Protection Agency (EPA) is in charge of determining and reporting fuel economy ratings for cars. Think of those large window stickers on a new car%u00a0that indicate the car%u2019s rating. Here are the EPA estimates of highway gas mileage in miles%u00a0per gallon (mpg) for a random sample of 21 midsize car models manufactured in the same year.27EXAMPLEDavid Zalubowski/AP PhotoHow to Make a Dotplot1. Draw and label the axis. Draw a horizontal axis and put the name of the quantitative variable underneath it.2. Scale the axis. Find the smallest and largest values in the data set. Start the horizontal axis at a number equal to or less than the smallest value and place tick marks at equal intervals until you equal or exceed the largest value.3. Plot the values. Mark a dot above the location on the horizontal axis corresponding to each data value. Try to make all the dots the same size and space them out equally as you stack them.%u00a9 Bedford, Freeman & Worth Publishers. For review purposes only. Do not distribute.