1. What is a Frequency Polygon?

A frequency polygon is a graphical representation of data that shows the frequencies of classes in a frequency distribution. It is created by plotting points at the midpoints of class intervals with heights equal to the frequencies, and then connecting these points with straight lines.

2. How to Create a Frequency Polygon?

To create a frequency polygon:

1. Calculate the midpoint of each class interval
2. Plot points at (midpoint, frequency) coordinates
3. Connect these points with straight lines
4. Extend the line to the x-axis at both ends (with zero frequency)

3. When to Use Frequency Polygons

Frequency polygons are useful for:

• Comparing multiple distributions on the same graph
• Visualizing the shape of a distribution
• Showing trends in data over equal intervals
• Comparing data sets with different numbers of observations

4. Using the Calculator

Instructions: Enter class intervals in the format "10-20,20-30,..." and corresponding frequencies as comma-separated values. The calculator will plot the frequency polygon automatically.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between a histogram and frequency polygon?
A: A histogram uses bars to represent frequencies, while a frequency polygon uses points connected by lines.

Q2: Why extend the polygon to the x-axis?
A: This creates a closed shape (polygon) and helps visualize the complete distribution.

Q3: Can I compare two distributions with this?
A: Yes, you can overlay multiple frequency polygons on the same axes for comparison.

Q4: What if my class intervals are unequal?
A: Frequency polygons work best with equal class intervals. Unequal intervals may distort the visual representation.

Q5: How is this different from an ogive?
A: An ogive shows cumulative frequencies, while a frequency polygon shows individual class frequencies.