A frequency chart shows how often something occurs. For example, a frequency chart of animals found in a forest would show how many of each animal were found. In order to find percentages in a frequency chart, you need to add together all the frequencies on the chart to find a total. Then, the percentage is just the number of times a specific event occurs divided by all the events.
Find the frequency of what you want to find the percentage of. Your frequency chart will display this. For example, assume you want to find the percentage of children in a school who weigh between 150 pounds and 159 pounds. On your frequency chart, it shows 42 people are between these weights.
Find the total number in the population. In the example, assume there are 300 people in the school.
Divide the frequency by the total population. In the example, 42 divided by 300 equals 0.14, or 14 percent.