How to Find Class Width for a Frequency Distribution Table

To find the class width for a frequency distribution table, subtract the smallest value in the data set from the largest value. Then, divide this result by the number of classes you want to have in the table. Mathematically, it’s:

Class Width = (Largest Value − Smallest Value)/Number of Classes

In this article, we will learn how to find the Class Width for a Frequency Distribution Table and discuss some examples.

What is Class Width?

Class Width refers to the difference between a class's upper and lower boundaries in a frequency distribution. It represents the size or span of each interval or group in which data is categorized.

To calculate class width, subtract the lower boundary of a class from the upper boundary of the same class:

Class Width = Upper Boundary − Lower Boundary

Alternatively, if all classes in a frequency distribution have equal width, you can find the class width by subtracting the lower boundary of one class from the lower boundary of the next class.

What is a Frequency Distribution Table?

A Frequency Distribution Table is a table that organizes data into different intervals (or classes) and displays the frequency (number of occurrences) of data points within each interval. It provides a visual summary of how the data is distributed across different categories or ranges.

Example of a Frequency Distribution Table:

In this example, the data is divided into four class intervals, and the table shows the frequency of data points within each interval.

Steps to Find Class Width for a Frequency Distribution Table

To find the class width for a frequency distribution table, follow these steps:

• Identify the Class Boundaries or Limits: Start by identifying the lower and upper boundaries (or limits) of each class interval.

• Calculate the Class Width: Subtract the lower boundary of the class from the upper boundary. If the classes are uniform, the class width will be consistent across all intervals. Alternatively, subtract the lower boundary of one class from the lower boundary of the next class.

• Check Consistency: Ensure that the class width remains consistent across all intervals if a uniform class width is required.

Solved Problems

Problem 1: Given the class intervals in a frequency distribution table. Find the class width.

Solution:

Choose any class interval, for example, 10 - 20.

Class Width = 20 − 10 = 10.

Thus, the class width for this distribution is 10.

Problem 2: Given the following class intervals. Find the class width.

Solution:

Class Width = 15 − 5 = 10.

So, the class width is 10.

Problem 3: For a set of class intervals with boundaries as follows. Find the class width.

Solution:

Class Width = 75 − 60 = 15.

Here, the class width is 15.

Read More,

• Statistics
• Frequency Distribution