Percent of a Total
Part of the Expressions & Data section of Coddy's Pre-Algebra journey. Lesson 41 of 52.
A class records what each student chose for lunch:
| Lunch | Students |
|---|---|
| Pizza | 10 |
| Salad | 6 |
| Soup | 9 |
What percent chose pizza? First find the total: the Students column adds to 10 + 6 + 9, which is 25. Then take the part over the total and multiply by 100: (10/25) × 100 is 40, so 40% chose pizza. It is the same step as turning a chance into a percent, because the part over the total is a fraction of the whole.
Why a percent? It compares groups of different sizes on one scale. 10 of 25 and 12 of 40 are hard to compare, but 40% and 30% are not. And the percents of all the rows add up to 100%, since together the rows make the whole: here 40%, 24% and 36%. That makes a handy check.
Challenge
A class records how its students get to school:
| Way to school | Students |
|---|---|
| Walk | 12 |
| Bus | 18 |
| Car | 6 |
| Bike | 4 |
Find the percent p of the students who take the bus. Write the percent as a number alone.
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: Sequences8Tables and Charts
Reading a TableTotals and DifferencesReading a Line GraphPercent of a TotalRecap: Tables and Charts3The Distributive Property
Number PropertiesMental MathDistributing LettersDistributing a MinusRecap: Distributing