How to Find Cumulative Frequency?

Answer: To find the cumulative frequency, add the frequency of each class or group to the sum of the frequencies of all preceding classes or groups.

Cumulative frequency is a running total of frequencies through the classes in a frequency distribution. It shows the number of observations that fall below the upper boundary of each class. To calculate it, start with the first frequency count, then add the second frequency to the first, the third to the sum of the first two, and continue this process until all classes are included.

For example, if the frequencies of four consecutive classes are 5, 8, 10, and 7, the cumulative frequencies are calculated as follows:

• First class: 55
• Second class: 5+8 = 13
• Third class: 13 + 10 =23
• Fourth class: 23+7 = 30

This process shows that, for instance, 23 observations fall within or below the third class.

Hence, finding cumulative frequency involves sequentially adding each class’s frequency to the total of the previous classes, providing a running total that helps in understanding the distribution of data.