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JJ.4 Find the range

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What is the range?

Range is a measure of how spread out a set of numbers is. It tells you the difference between the largest value and the smallest value in the data set.

Example:
  • Data set: 3, 7, 10, 12
  • Largest number: 12
  • Smallest number: 3
  • Range: 12 − 3 = 9
Note

The range shows how far apart the numbers are. A larger range means the numbers vary more.

How do you find the range?

To find the range, identify the greatest and least values in the set, then subtract the least value from the greatest value.

Steps:
  • Write down the data: 15, 22, 18, 25, 20
  • Greatest value: 25
  • Least value: 15
  • Subtract: 25 − 15 = 10
  • The range is 10.
Note

You must always compare the greatest and least values. Order the numbers first if it helps you see them clearly.

Why is the range important?

The range helps you understand how consistent or spread out the numbers are. It is useful when analyzing patterns or comparing data sets.

Example:
  • Class A test scores range: 5
  • Class B test scores range: 20
  • Class B’s scores vary more because the range is larger, meaning the scores are spread farther apart.
Note

A smaller range means the numbers are closer together. This often shows more consistency in the data.

Using range with real-world data

The range can help you compare different sets of information in everyday life, such as temperatures, distances, scores, or times.

Examples:
  • Temperatures this week: 48°F to 63°F → Range: 63 − 48 = 15°F
  • Lap running times: 72 sec to 81 sec → Range: 81 − 72 = 9 sec
  • Height of plants: 25 cm to 40 cm → Range: 40 − 25 = 15 cm
Note

Finding the range helps you understand how much the values change over time or between items.