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**Finding a percent of a number Textbook pages 434-440**

January 14th, 15th, 16th

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**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

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**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.

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**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

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**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?

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**Try some more! Find 25% of 48 12, explain how you found your answer**

8.5 45% 0f 20 9 60% of 60 36

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**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

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**Try some! 20% of what number is 30 150 40% of what number is 60**

72

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**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.

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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

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**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

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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.

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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.

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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 $ = $9.54

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**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 $ There is a 5% sales tax. What is the total amount of your purchase. $30.24

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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?

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**Simple Interest Interest paid on only the principal. Formula**

SI=Principal x annual interest Rate x Time in years

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Percent of change This can be either percent increase or percent decrease. P%=amount of increase/original amount P%=amount of decrease/original amount What is the percent change from 8 to 13? 62.5% What is the percent change from 60 to 12? 80%

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Try some. A taco company puts 24 taco shells in every box. Recently the company expanded the box and put 25% more shells in each box. How many more shells are in each box? 25% of 24 .25 x 24 = 6 = 30 shells

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Finding the mark-up A store that sells skateboards buys them from a manufacturer at a wholesale price of $57. The store’s mark-up is 150%. What is the retail price?

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