How do you construct a frequency polygon from a histogram?

Ditching the Bars: How to Turn a Histogram into a Smooth Frequency Polygon

Histograms and frequency polygons? Yeah, they both show you how data is spread out. Think of a histogram as a cityscape of bars, each one telling you how many data points fall into a certain range. A frequency polygon, on the other hand, takes that same information and smooths it out into a line graph. And guess what? You can totally build a frequency polygon right from a histogram. It’s like turning blocky LEGOs into a sleek, flowing sculpture. Let’s see how it’s done.

Histograms and Frequency Polygons: A Quick Refresher

Before we get our hands dirty, let’s quickly recap what these things are all about.

• Histogram: Imagine a bar chart, but instead of showing categories, it shows ranges of numbers. The height of each bar tells you how often numbers fall into that range. It’s a great way to get a feel for where your data clumps up.

• Frequency Polygon: Now, picture connecting the dots on a histogram with a line. That’s basically a frequency polygon! Instead of bars, you get a line that shows the shape of the data’s distribution. It’s especially handy when you want to compare two different sets of data on the same graph – way easier to see the differences than with a bunch of overlapping bars.

Think of it this way: the histogram is the raw data, and the frequency polygon is the artist’s interpretation.

From Histogram to Polygon: Step-by-Step

Ready to transform those bars into a smooth line? Here’s the lowdown:

A Real-World Example

Let’s say we’re looking at a histogram of students’ test scores:

Score RangeNumber of Students60-70570-801080-901590-1008