Finding a percent of a number Textbook 449-493

1. Finding a percent of a numberTextbook 449-493 January 13th 14th, 15th, 16th

2. Objective • I can find the percent of a quantity. • I can solve problems involving finding the whole, if given the part of the whole and percent

3. Review Vocabulary • Is means • Equal = • Of means to • multiply. • Equations are going to be very important in this lesson. • Reminder, in order to solve equations you have to do the opposite.

4. New Vocabulary • Interest: is the amount paid to use money. • Principal; the amount of money you borrow or save. • Annual interest rate:the amount of money you earn or pay per year

5. Finding the percent of a Number • There are three ways to find the percent of a number. • Change the percent to a decimal then multiply. • Change the percent to a fraction then multiply. • By making a proportion. • Lets see what you find easier. • 50% of 8 • What way did you use?

6. Try some more! • Find 25% of 48 • 12, explain how you found your answer • 10% of 85 • 8.5 • 45% 0f 20 • 9 • 60% of 60 • 36

7. Find the whole number given the part and percent • 25% of what number is 8 • Rewrite as an equation. • .25 x n = 8 • How do I solve? • Divide both sides by .25 • The answer is 32

8. Try some! • 20% of what number is 30 • 150 • 40% of what number is 60 • 150 • 75% of what number is 54 • 72

9. Finding a discount • What is a discount? Give me an example • The discount is the amount that you will get off of the regular price. • Find the discount, (by finding the percent of the number) usually a percent off. • Then subtract from the original price, the answer you get is the sale price.

10. Example • A pair of pants cost $36. The sale price is 25% off the regular price. What is the sale price? • 25% of $36 • What are we going to change 25% to. • 0.25 x $36 • $9 • Then subtract from the original price. • $36-$9 • $27 is he sale price of the pants

11. Try some • A regular price for a shirt is $40. • Find the sale price if the discount is 15%. • $34 • Find the sale price if the discount is 40% • $24

12. Is there another way! • Can anyone think of another way to do these types of problem. • If you know that you will not have to pay the discount part, you will pay whatever percent is left. • If there is a 30% discount, that means you will pay 70% of the amount. This eliminates one step.

13. Finding Sales Tax • Sales Tax is something extra you have to pay besides the price of something. • Anyone know what the sales tax is in Lorain county? • Find the sales tax the same way you find the percent of a number, then add that to the original number.

14. Example • You are buying cat food for $9. The sales tax is 6%. What is the total of the purchase? • 6% x 9 • 0.06 x 9 • .54 cents • $9.00 + .54 = $9.54

15. Try One! • Cat toy is $8.00. The sales Tax is 6%. What is the cost. • $8.48 • You are buying a pair of shoes that cost $28.80. There is a 5% sales tax. What is the total amount of your purchase. • $30.24

16. Tips • A tip is added to the total of a bill. It is found the same way that you find the percent of a number. • Standard tipping amount is what?

17. Simple Interest • Interest paid on only the principal. • Formula • SI=Principal x annual interest Rate x Time in years