The document discusses percentages and solving percentage equations. It provides examples of how to write percentage equations for word problems, such as finding what percentage one number is of another or finding the total given a percentage. It demonstrates solving equations to find percentages and totals in various contexts like test scores, class sizes, sales, and more. Percentages allow for easier comparison of quantities and are used in many everyday situations like grades, weather, nutrition labels, and shopping.

1. Percent Equations September 1, 2010

2. A percent can tell you about the significance of a quantity. The humane society found homes for 6 more puppies this month than last month. Is this a big change? If I was told this was a 100% increase over last month, the answer is yes. If this is a 1% increase over last month, then the increase of 6 puppies is not much of a difference. Why do we need percents

3. A percent can make it easier to compare quantities. I could say that I scored a 18/25 on Quiz 1 and a 30/40 on Quiz 2. If I use percents rather than fractions, the comparison would be more obvious: I scored a 72% on Quiz 1 and a 75% on Quiz 2. Why do we need percents?

4. Grades Weather Forecast Chance of precipitation Nutritional Labels Download Status Shopping Sales Tax Discounts When do we see percents?

5. Percent literally means “per hundred.” A percent is like a ratio because it compares a number to 100. Understanding Percent

6. Decode the question into an equation. Change percent to decimal. Solve the equation. Solving Percent Equations

7. What is 20% of 60? What is 5% of 120? Solving Percent Equations x = 0.20 • 60 X = 12 x = 0.06 • 120 X = 6

8. You are reading a book. You have read 60% of the book. It has 700 pages. How many pages have you read? What is 60% of 700? Book Problem x = 0.60 • 700 X = 420 pages

9. 12% of what is 21? 40% of what is 90? Solving Percent Equations x = 0.12 • 21 .12 .12 x = 175 = 0.4 • 90 x .4 .4 x = 225

10. 7 students in Algebra 1 have A’s. They make up 25% of the class. How many students are in the class? 25% of what is 7? Students in a class x = 0.25 • 7 .25 .25 X = 28

11. What percent of 330 is 21? What percent of 30 is 48? Solving Percent Equations X • 330 = 21 330 330 x = 0.065 ≈6.4% X • 30 = 48 30 30 x = 1.6 = 160%

12. Six students make an F on the exam on Friday. There are 27 students in the class. What percentage of students failed the exam? What percent of 27 is 6? Solving Percent Equations X • 27 = 6 27 27 x = 0.22 ≈ 22.2%

13. 18% of what number is 9? What percentage of 200 is 40? 45 is what percent of 54? Exit Slip