What is the method to draw a frequency polygon from a histogram?

To draw a frequency polygon from a histogram, plot the midpoints of each bar and connect them with straight lines.

A frequency polygon is a useful way to display the distribution of data and can be drawn directly from a histogram. First, identify the midpoints of the top of each bar in the histogram. The midpoint is found by averaging the upper and lower boundaries of each class interval. For example, if a bar represents the interval 10-20, the midpoint would be (10 + 20) / 2 = 15.

Next, plot these midpoints on a graph, with the x-axis representing the class intervals and the y-axis representing the frequencies. Each midpoint should be plotted at the height corresponding to the frequency of that class interval.

Once all the midpoints are plotted, connect them with straight lines. Start from the first midpoint and draw a line to the next, continuing this process until all midpoints are connected. To complete the frequency polygon, you can extend the lines to the x-axis at the beginning and end of the data set, ensuring the polygon starts and ends at zero frequency.

This method provides a clear visual representation of the data distribution, making it easier to analyse trends and patterns compared to a histogram alone.