Goal:

- I can find percent increase and decrease.

Percent of Increase and Decrease

VocabularyPercent Change

A percent change is an increase or decrease given as a percent of the original amount.

A percent increase describes an amount that has grown. A percent decrease describes an amount that has been reduced.

Percent Change

Percent change = amount of increase or decreaseoriginal amount

This is expressed as a percentage! So you will have to be careful with decimals!

Find each percent change. Tell whether is a percent increase or decrease.

Percent change = amount of increase or decreaseoriginal amount

From 25 to 49

Percent change = 49 - 25 25

Percent change = 0.96 = 96%. This is a percent increase, why?

Find each percent change. Tell whether is a percent increase or decrease.

Percent change = amount of increase or decreaseoriginal amount

From 50 to 45

Percent change = 50 - 45 50

Percent change = 0.10 = 10%. This is a percent decrease, why?

YOUR TURN: Find each percent change. Tell whether is a percent increase or decrease.

1. From 200 to 110

2. From 25 to 30

3. From 80 to 115

Finding the result of a Percent Increase of Decrease

Find the result when 30 is increased by 20%

0.20(30) = 6

30 + 6 = 36

Find the result when 65 is decreased by 80%

0.80(65) = 52

65 – 52 = 13

YOUR TURN

1. Find the result when 72 is increased by 25%

2. Find the result when 10 is decreased by 40%

Vocabulary

Discount

A discount is an amount by which an original priced is reduced. Discount is a % of the original price. Final price = original price – discount.

MarkupA markup is an amount by which an original priced is increased. Markup is a % of the original price. Final price = original price + markup.

Discounts – two methodsAdmission to the museum is $8. Students receive a 15% Discount. How much is the discount? How much do students pay?

Method 1 – Discount is a percent decrease.

0.15(8) = 1.20

8 – 1.20 = 6.80Method 2 – Subtract percent discount from 100%.

100% - 15% = 85%

0.85(8) = 6.808 – 6.8 = 1.20

Christo used a coupon and paid $7.30 for a pizza that normally costs $10.50. Find the percent discount.

$10.50 - $7.35 = $3.15

$3.15 = x(10.50)

0.3 = x

The discount is 30%

10.50 10.5

3.15 10.50

0

x

YOUR TURN

1. A $220 bicycle was on sale for 60% off. Find the sale price.

2. Ray paid $12 for a $15 T-shirt. What was the percent discount?

Markups – two methodsCaleb buys a necklaces at a wholesale cost of $48 each. He then marks up the price by 75% and sells them. What is the amount of the markup? What is the selling price?Method 1 – Markup is a percent increase.

0.75(48) = 36

48 + 36 = 84Method 2 – Add the markup to 100%.

100% + 75% = 175%

1.75(48) = 8484 – 48 = 36

Lars purchased a daily planner for $32. The wholesale cost was $25. What was the percent markup?

32 – 5 =27

7 = x(25)

0.28 = x

The discount is 28%

7 2

25 5

5

2

x

YOUR TURN

1. A video game has a 70% markup. The wholesale cost is $9. What is the selling price?

2. What is the percent markup on a car selling for $21,850 that had a wholesale price of $9500?

Review Stuff

How do I find percent of change?

What is the difference between a markup and a discount?

Homework

Turn in your Homework!!!!