1. Percents

2. What is percent? Percent (or per cent) means “per 100” or “out of 100” For example: If you answered 90 out of 100 questions correctly on a test you would receive 90 percent (or 90%) That’s an A!

3. What is percent? What if your test only had 10 questions and you got 9 correct? 9 out of 10 or is equal to what percent? You could set up a RATIO to find your score. 9 10 9 = ? 10 100 Cross multiply 9 X 100 = 900 Then divide 900 ÷ 10 = 90 or 90%

4. Try these 1 = ? 2 100 3 = ? 5 100 Cross multiply 1 X 100 = ? Then divide ? ÷ 2 = ? % Cross multiply 3 X 100 = ? Then divide ? ÷ 5 = ? % 2 = ? 25 100 Cross multiply 2 X 100 = ? Then divide ? ÷ 25 = ? % Cross multiply 1 X 100 = 100 Then divide 100 ÷ 2 = 50 % Cross multiply 3 X 100 = 300 Then divide 300 ÷ 5 = 60 % Cross multiply 2 X 100 = 200 Then divide 200 ÷ 25 = 8 %

5. Now in reverse Suppose you are given a percentage and need to find the equivalent fraction (this happens in real life) For example 10 percent of 20 is what? This questions looks like this: 10 = ? 100 20 Work your ratio Cross multiply 10 X 20 = 200 Then divide 200 ÷ 100 = 2 or 2% 10 out of 100 of

6. Real life example You are at a restaurant and need to leave a tip for the great service you received. It is normal to leave a tip of 20% for good service. Your bill was $40. What should you leave as a tip? 20 percent of 40 is what? Work your ratio - Cross multiply 20 X 40 = 800 Then divide 800 ÷ 100 = 8 or $8 20 = ? 100 40 20 out of 100 of You should leave a tip of $8

7. Try this A jacket you want is 25% off. The regular price is $50. How much less will you have to pay? What should you leave as a tip? 25 percent of 50 is what? Work your ratio - Cross multiply 25 X 50 = ? Then divide ? ÷ 100 = ? 25 = ? 100 50 20 out of 100 of

8. Did you get A jacket you want is 25% off. The regular price is $50. How much less will you have to pay? What should you leave as a tip? 25 percent of 50 is what? Work your ratio - Cross multiply 25 X 50 = 1250 Then divide 1250 ÷ 100 = 12.50 25 = ? 100 50 20 out of 100 of Your jacket will cost $12.50 less $50 - $12.50 = $37.50

9. The End Please see the teacher for today’s assignment