The Lesson
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.Question
The frequency table below shows the test scores for a class of students. What is the range of the test scores?Step-by-Step:
1
Make sure the entries in the Score column are in numerical order. In our example, the entries are in numerical order.
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.
In our example, the lowest entry is 5. The lowest test score is 5.
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.
In our example, the highest entry is 10. The highest test score is 10.
3
Subtract the lowest number (5) from the highest number (10).
10 − 5 = 5
Answer:
The range of the test scores is 5.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