Graphing—continued

Step 3. Scale Choosing a scale and marking it accurately on the graph is very important. Sometimes it can be tricky to find a scale that displays the data effectively. Look at the data for the independent variable. What is the smallest number you will need to plot? What is the largest number you need to plot? This will influence the scale on the x-axis. Look at the data for the dependent variable. What is the smallest number you will need to plot? What is the largest number you need to plot? This will influence the scale on the y-axis.

Making a scale for each axis is like making a ruler. Spacing must be the same, and your numbers must go up by equal amounts. In detail, here are rules about the scale you choose: Each division on the x axis must be equal. Each division on the y-axis must be equal. The divisions on the x-axis may or may not equal the divisions on the y-axis. (For example, you could count by twos on the x-axis and count by fives on the y-axis.) We need our x-axis to go from 0 to 16. Since the time is measured in 2-minute intervals, and we only need to go from 0 to 16, let’s count by 2s on the x-axis. We need our y-axis to go from 0 to 58. Let’s count by 5s on the y-axis and go from 0 to 60.

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