Frequency Polygons Examples
Example 1: The frequency data below was used to create a frequency polygon.
| Class Interval | Frequency |
|---|---|
|
49.5-59.5 |
5 |
|
59.5-69.5 |
10 |
|
69.5-79.5 |
30 |
|
79.5-89.5 |
40 |
|
89.5-99.5 |
15 |
Solution:
By first determining the classmark using the equation Classmark = (Upper Limit + Lower Limit) / 2, we may build a frequency polygon without a histogram. Additionally, by combining the previous and next frequencies, we can get the cumulative frequency of each class interval.
Class Interval:
- (59.5 + 49.5/2) = 54.5
- (69.5 + 59.5/2) = 64.5
- (79.5 + 69.5/2) = 74.5
- (89.5 + 79.5/2) = 84.5
- (99.5 + 89.5/2) = 94.5
Class Interval Lower Bound Upper Bound Classmark Frequency 49.5-59.5
49.5
59.5
54.5
5
59.5-69.5
59.5
69.5
64.5
10
69.5-79.5
69.5
79.5
74.5
30
79.5-89.5
79.5
89.5
84.5
40
89.5-99.5
89.5
99.5
94.5
15
We note the before and after classmarks as well while plotting the graph. The before in this instance is 44.5, while the after is 104.5. The scores are shown on the x-axis, while the frequency is indicated on the y-axis. Consequently, the frequency polygons graph will seem like follows:
Example 2: Assume that a class of 65 students’ weights are distributed as follows: 15 – 25, 25 – 35, 35 – 45, and 45 – 55. How many grade points would there be for each weight category?
Solution:
Formula used to get the classmark for a Frequency Polygon Graph is:
Classmark = (Upper Limit + Lower Limit) / 2
Hence,
- Class interval 15-25 = (15 + 25)/2 = 20
- Class interval 25-35 = (25 + 35)/2 = 30
- Class interval 35-45 = (35 + 45)/2 = 40
- Class interval 45-55 = (45 + 55)/2 = 50
Frequency Polygons in Statistics
Frequency Polygons in Statistics: A frequency polygon is a type of line graph where the frequencies of classes are plotted against their midpoints. This graphical representation closely resembles a histogram and is typically used for comparing data sets or showing cumulative frequency distributions. It uses a line graph to represent quantitative data.
Frequency polygons are one of the great methods to represent statistical data so that it can be read easily. In statistics, we deal with lots of data, and reading it quickly is necessary for solving statistical problems effectively.
Frequency polygons help us to achieve the same result. In this article, we will learn about frequency polygons, their formula, examples, and others in detail.
Frequency Polygons
Table of Content
- What is a Frequency Polygon in Statistics?
- Frequency Polygon Graph
- Cumulative Frequency Polygon
- How to Draw Frequency Polygon?
- Histogram and Frequency Polygons
- Frequency Polygons Examples
- Frequency Polygons Are Used For – Applications