Activator You bought a shirt that was

Activator • You bought a shirt that was 45% of the original price. The shirt was $27. What was the original price?

Percents of a Number • This phrase will help you set up and solve all problems involving percent. • Is over of = percent over 100= is/of = %/100 • The question will tell you where each number should go using is, of, and percent

Is / of = % / 100 What is 20% of 60 = 12 is what % of 60 Or What % is 12 of 60 = 12 is 20% of what number =

Is / of = % / 100 What is 20% of 60 is 60 = 12 is what % of 60 Or What % is 12 of 60 20 12 100 60 You may use any method to solve this proportion that you prefer. = 12 is 20% of what number % 12 100 of You may use any method to solve this proportion that you prefer. 20 = 100 You may use any method to solve this proportion that you prefer.

Set up the proportion of each problem Number the problem, do not erase, I will check all three. Set up each problem using the proportion Solve.

Another way to solve % of number problems:

Another way to solve % of number problems: Here is an easy way to remember how to write the equation: Is = % of number If you substitute the word of for the times sign it will help you set your equation up correctly.

Homework • Workbook pg. 87 -88

Activator • Chris bought a sweater that had been marked up 23% by the retail store, but he had a coupon for 15% off. The sweater was originally $56 before the mark up. How much was the mark up? How much was the discount his coupon gave him? What was the total if he paid 9% sale tax?

Finding Discounts • • Discounts are the money you save on a purchase. 2 things to be aware of: 1. If the question asks for the discount you are just finding the money you saved. 2. If the question asks for the “sale price” or “discounted price” you are finding the new total. (subtract the discount from the original price)

Finding Discounts • To find discount: Percent saved x Original Price = Discount • To find “sale price” or “discounted price” Original Price – Discount (percent saved x original price) = Sale Price

Finding Discounts • Mark bought a sweater that was on sale for 30% off the original price of $48. 00. How much did he save? What was the sale price? 1. How much did he save: % x op = 2. What was the sale price: op – (% x op) =

Finding Mark Ups • • Mark ups are how much money was added to the price from the manufacturer to the retailer. 3 things to be aware of: 1. If the question asks for the mark up you are just finding the money that the item increased. 2. If the question asks for the “price” or “retail price” you are finding the new total. (add the mark up to the original price) 3. Sometimes the original price is called the “wholesale price”

Finding Mark Ups • To find mark ups: Percent marked up x wholesale Price = mark up • To find “price” or “retail price” Original Price + Mark up (percent mark up x wholesale price) = Retail Price

Finding Mark Ups • Mark bought a bottle of shampoo that was wholesale for $2, but Wal-mart marked up the price 200% How much was the mark up? What is the retail price? 1. How much was the mark up: % x ws p = 2. What is the retail price: ws p + (% x ws p) =

Find the Sale Price: You find a sweater on sale for 30% off. The sweater is originally $72. What is the sale price of the sweater?

Finding Sales Tax • • Sales tax is the money you pay extra for taxes. 2 things to be aware of: 1. If the question asks for the sales tax you are just finding the money you pay extra. 2. If the question asks for the “total cost” or “cost” you are finding the new total. (add the sales tax to the original price)

Finding Sales Tax • To find sale tax: Percent taxed x Original Price = sales tax % x $ = sales tax • To find “total cost” or “cost” Original Price + sales tax (percent taxed x original price) = total cost $ + sales tax = total cost or $ + (% x $) = total cost

Finding Sales Tax • Mark bought a sweater that was $48. 00. The tax for his state is 8. 75%. How much was the tax? What was the total cost? 1. How much was the tax: % x op = 2. What was the total cost: op + (% x op) =

Finding Tips • • Tips are the money you give someone for a good job. 2 things to be aware of: 1. If the question asks for the tip you are just finding the money you leave. 2. If the question asks for the “total cost” or “cost” you are finding the new total. (add the tip to the original price)

Finding Tips • To find tip: Percent tip x Original Price = tip % x $ = tip • To find “total cost” or “cost” Original Price + tip (percent tip x original price) = Total Cost $ + tip = total cost or $ + (% x $) = total cost

Finding Tip • Mark and his family went to dinner at Olive Garden. Their food bill was $56. 78. They want to leave a 15% tip for their server. The tax is 9. 5% How much was your tip? How much was your tax? What was the total cost of the meal?

Short Cut for finding the total cost and retail price add 100% to your % then multiply that % by the original price. Example: Cost = $5. 62 tax rate = 6% $5. 62 x 106% = $5. 9572 = $5. 96

Regular Workbook pg. 123 -124

Summarizer • Chris bought a sweater that had been marked up 23% by the retail store, but he had a coupon for 15% off. The sweater was originally $56 before the mark up. How much was the mark up? How much was the discount his coupon gave him? What was the total if he paid 9% sale tax?

Homework • Pre-Algebra Workbook pg. 97 -98

Simple Interest • How many of you have your own bank account? • Do you know what happens every 3, 6, or 12 months? • How many have heard the term refinancing? What does it mean?

Copy the box:

Simple Interest • To Find Simple Interest use the following formula: I = Prt • • I = interested earned P= Principal ($ you started with) R = Annual interest rate or (%) T = Time in years. (if the time is given in months, rate the month as a fraction over 12: Example 7 months = 7/12) Copy all above

Simple Interest • To find a balance: you add the interest to the principal. • P + I = balance (if you don’t know the interest or principal you will need to solve for them) • If the balance is given then you will need to subtract either the interest or the principal from the balance to find the (interest or principal) • To find any missing part of the Interest formula: You multiply to two pieces of information given and then divide the interest by that product. Example: You want to find the rate: $450 = $300 x (r) x 3 years $450 = 900 r 900 0. 5 = r = 50% try to turn you decimals for rates back into percent form.

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Using I = prt If you are trying to find an amount other than the interest, CSP! Substitute the amounts you know, and solve algebraically for the amount you need. You deposit $600 into a 6 month CD. After 6 months, the balance is $618. What is the interest rate? *The interest earned is the balance minus the principal! **1/2 year =0. 5. ($18 is the interest because you started with $600 and had a balance of $618 so you would subtract them) I = prt 18 = 600 * r * 0. 5 18 = 300 r (divide both sides by 300) 300 0. 06 = r, so the rate is 6%.

Pair/Share • You deposit $1000 into a 3 -month certificate of deposit (CD). After 3 months the balance is $1005. Find the simple annual interest rate! I = Prt $5 = $1000 x r x 3/12 $5 = 250 r 250 0. 02 = r = 2%

Again! • Find the time: You put $750 into a CD. Your simple annual interest rate is 4%. How long will it take you to earn $150 in interest? • I = Prt • Find the principal: You earn $84 interest on a 2 -year CD that pays 7%. What was the original principal? • I = Prt

Homework 125 -126 all

Tic-Tac-Think: Simple Interest Choose one task from each column to answer completely. Solve: You have a principal of $540 with a rate of 3. 5% for 8 years. What will your balance be? Solve: You have a principal of $2200 with a rate of 6% for 8 months. What will your balance be? Solve: You have a principal of $758 with a rate of 0. 25% for 5 years. What will your balance be? Find the missing value How do you find the I= 40 interest if you know P= $520 the balance and the R= principal? T= 3 years How do you principal if you know the interest and the balance? How do you find simple interest? Find the missing value I= P= $780 R= 7. 5% T= 4 months Find the missing value I= 120 P= $1260 R= 5% T=

Percent Increase or Decrease Percent of change = Difference of the two numbers Original amount

• Wal-mart sold a stereo for $98. Someone who bought that stereo was able to sell it on Ebay for $118. What was the percent change?

Error Analysis • Chad bought a new basketball goal for his son for $400. He saw the same goal three weeks later on sale for $250. What was the percent increase or decrease? 400 -250 150 250 60% decrease

Tip, Interest, Percent of a # Find a Tip Multiply the percent you want to leave by the cost of the meal. Or you could double the tax: This is about a twenty percent tip. Or you can find 10% then half of that and add the two answers to get the total tip. Round to nearest whole number. All Percents Must be in decimal form before you multiply!! Simple interest The Formula: Prt. P= Principle x r=rate x t=time You put $30 dollars in a savings account that earns 8% interest for 3 years how much will you earn. 30 x. 08 x 3 = $7. 20 What percent is a number of another number What percent is 12 of 38? Write the problem as a fraction equal to another fraction with 100 on the bottom. Example: 12 / 38 = ? / 100 Cross multiply the numerator and denominator diagonal of each other. Divide by the denominator not used. 12 x 100 = 1200 ÷ 38 = 31. 58(rounded) or write the ratio as fraction, turn into a decimal, turn decimal into a percent: 12/38 = 12 ÷ 38 = 0. 3157, move decimal right twice = 31. 57%