1. Percents As Ratios How treating percents as ratios can simplify your work

2. What is a percent? Percent means parts per hundred parts: There are 100 stars here. There are 3 red stars per hundred total, or 3% of the stars are red. There are 97 yellow stars per hundred total, or 97% of the stars are yellow.

3. There are 300 stars here. There are 9 red stars per three hundred total. 9/300 = 3/100 3% of the stars are red. There are 291 yellow stars per three hundred total. 291/300 = 97/100 97% of the stars are yellow.

4. Percents ARE ratios Let’s try to picture, instead, ‘per cent’ or: % When most of us think about percents, we picture: per hundred Continue….

5. How does this help? Problem 1: Write 75% as a fraction: Easy!! “3/4” Who needs ratios?? Continue….

6. Problem 2: Write 0.0196% as a fraction: Huh? Continue….

7. Problem 2: Write 0.0196% as a fraction: Wait… 0.0196% is 0.0196 per cent Continue….

8. Problem 2: Write 0.0196% as a fraction: 0.0196 100 0.0196 per cent is: 0.0196 per hundred or 0.0196 100 Hurray!

9. Problem 3: Convert 0.017 to a percent. I bet you can use ratios for this too… Continue…

10. Problem 3: Convert 0.017 to a percent. I want to know… 0.017 = ? percent, or ? per hundred: 0.017 = ? 100 Solve…

11. Problem 3: Convert 0.017 to a percent. 1.7% 0.017 = ? 100 (0.017)(100) = ? 1.7 = ? So: 0.017 = 1.7/100 or 1.7% Hurray!

12. Percents Quiz Write 0.816% as a fraction: Write 0.12 as a percent: Continue…

13. Percents Quiz Write 0.816% as a fraction: 0.816 100 Write 0.12 as a percent: 0.12 = ? 100 12 = ? 0.12 = 12%