The Range
Part of the Expressions & Data section of Coddy's Pre-Algebra journey. Lesson 31 of 52.
The range measures how spread out a list is: the highest value minus the lowest. Daily highs of 12, 19, 15, 31 and 22 degrees have a range of 31 - 12, which is 19. The warmest day was 19 degrees warmer than the coolest.
With a negative lowest value, you subtract a negative. Highest 5, lowest -9: 5 - (-9) is 5 + 9, which is 14. The number line agrees: from -9 up to 0 is 9 steps, and from 0 up to 5 is 5 more.
A range is never negative, because the highest value is never below the lowest. A negative range means the subtraction went the wrong way round. Two lists can share the same mean and still have very different ranges, which is why a range is often reported next to an average.
Challenge
Over one week, the midday temperatures in a mountain town were 3, -4, 11, 18, 7, -1 and 9 degrees. Find the range r. Write r equal to the highest value minus the lowest, then work it out.
Test yourselfThis lesson includes a short quiz. Start the lesson to answer it and track your progress.
Test yourselfThis lesson includes a short quiz. Start the lesson to answer it and track your progress.
All lessons in Expressions & Data
1Variables and Expressions
What a Variable IsWriting ExpressionsExpressions from StoriesTwo OperationsRecap: Expressions2Evaluating Expressions
Substituting a ValueNegative InputsPowers in ExpressionsFormulasRecap: Evaluating5Patterns and Sequences
Continuing a PatternThe Common DifferenceThe nth TermWriting the RuleRecap: Sequences3The Distributive Property
Number PropertiesMental MathDistributing LettersDistributing a MinusRecap: Distributing