Exploring Percents Graphically
- Author:
- Ivan Cheng
Percents are ratios that are equivalent to a comparison of a "part" to a "whole" and are based on 100 as the denominator.
Move the slider on the x-axis for the value of the "whole" (denominator).
Move the slider on the y-axis for the value of the "part" (numerator).
Move the red percent slider up or down for the percent value (expressed as a decimal).
To find the percent value for a part of a whole (e.g., 40 is what percent of 50?), first move the slider for the value of the "part" on the y-axis and the slider for the value of the "whole" on the x-axis. Then move the percent slider so that it passes through point A.
To find the percent of a whole (e.g., find 40% of 50), first move the percent slider to the correct value (e.g., p = 0.4). Then move the slider on the x-axis to the correct value (e.g., 50). Finally, move the slider on the y-axis so that point A is at the intersection of the percent line and the line formed by the slider on the x-axis.
To find the whole when given a part and a percent value (e.g., 40 is 50% of what number?), first move the slider for the "part" (y-axis) to the correct value (e.g., 40). Then move the percent slider to the correct value (e.g., p = 0.5). Finally, move the slider for the "whole" on the x-axis so that point A is at the intersection of the percent line and the line formed by the slider on the y-axis.
- When finding the ratio of a part to a whole, what do you notice about the slope of the percent line?
- What happens to the percent value if you keep the value of the "part" constant and change the value of the "whole"? What makes the percent value increase? What makes the percent value decrease?
- What happens to the percent value if you keep the value of the "whole" constant and change the value of the "part"? What makes the percent value increase? What makes the percent value decrease?