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How to Find the Range from a Frequency Table (Mathematics Lesson)

Finding the Range from a Frequency Table

We can find the range of a set of numbers presented in a frequency table.

How to Find the Range from a Frequency Table

Finding the range from a frequency table is easy.

An Example Question

The frequency table below shows the test scores for a class of students.



What is the range of the test scores?
Step 1
Make sure the entries in the Score column are in numerical order. In our example, the entries are in numerical order.

Step 2
Find the lowest entry in the Score column (with a Frequency greater than 0).



In our example, the lowest entry is 5. The lowest test score is 5.

Step 3
Find the highest entry in the Score column (with a Frequency greater than 0).



In our example, the highest entry is 10. The highest test score is 10.

Step 4
Subtract the lowest number (5) from the highest number (10).
10 - 5 = 5
The range of the test scores is 5.

A Real Example of How to Find the Range

The slider below gives another example of finding the range from a frequency table.
Interactive Test
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Here's a second test on finding the range from a frequency table.
Here's a third test on finding the range from a frequency table.
Beware

Make Sure the Numbers Are in Order

Make sure the numbers in the left most column are in order.



Don't forget: The whole row, not just that in the first column, needs to be rearranged. Each number in the Frequency column corresponds to the Number to its left.

Careful of 0 Frequencies

What is the range of the frequency table below?



It is tempting to think that it is:
Range = 4 - 1 = 3
However, Number 1 and 4 have a Frequency of 0. That means there is actually no 1 and 4 in the set of numbers. Just ignore any row with a Frequency of 0.

The true range is:
Range = 3 - 2 = 1