What is Percent of Change?Common Examples of

Percent of IncreaseCommon Examples of Percent of Decrease

Sales tax on an item purchased

Items that are on sale at a store

Finding a total bill at a restaurant including tip

Population decreases

Percent of ChangePercent of Change: the amount, stated as

a percent, that a number increases or decreases.

Percent of Increase: The amount, stated as a percent, that a number goes up.

Percent of Decrease: The amount, stated as a percent, that a number goes down.

Percent of Change

Percent of Change = amount of change

original amount

Finding Percent of Change27 is decreased to 20

27 – 20 = 7 Percent of Change = amount of change

original amount Percent of Change = 7

27 Percent of Change ≈ 0.259259 Percent of Change ≈ 25.9%

Finding Percent of Change32 is increased to 67

67 – 32 = 35 Percent of Change = amount of change

original amount Percent of Change = 35

32 Percent of Change ≈ 1.09375 Percent of Change ≈ 109.4%

Finding Percent of Change20 is decreased to 11

20 – 11 = 9 Percent of Change = amount of change

original amount Percent of Change = 9

20 Percent of Change ≈ 0.45 Percent of Change ≈ 45%

Finding Percent of Change42 is increased to 72

72 – 42 = 30 Percent of Change = amount of change

original amount Percent of Change = 30

42 Percent of Change ≈ 0.71428 Percent of Change ≈ 71.4%

Finding Percent of Change Your Turn…

24 is increased to 30 Percent of Change = amount of change

original amount

Finding Percent of Change Your Turn…56 is decreased to 14

Percent of Change = amount of change

original amount

Finding Percent of Change Your Turn…105 is decreased to 32

Percent of Change = amount of change

original amount

Finding Percent of ChangeWord Problems

Zack Cole shot an 86 on the golf course on Monday. On Friday he shot a 95. What is the % of change?

•86 increased to 95

Percent of Change = amount of change = 9 original amount 86

Percent of Change = 10.5%

Finding Percent of ChangeWord ProblemsKelly Dyer became a great writer. She had a picnic each year to celebrate the date of her first published work. The 1st year 50 people came. The 2nd year 30 people came. What is the percent of change?

•50 decreased to 30 Percent of Change = amount of change = 20 original amount 50

Percent of Change = 40%

Finding Percent of ChangeWord Problems: Your TurnLast six weeks Joseph Lawhorn made

an 88. This six weeks he made a 92. Please figure the percent of change.

Finding Percent of ChangeWord Problems: Your TurnAngela Smyre became a famous

architect. She made $90,000 in 2004. In 2005 she made $120,000. What is the percent of increase?

Finding Percent of ChangeWord Problems: Your TurnAmber Robinson became a foster

mother, because she is so good with children. She took care of 8 children in 2003. In 2004 she had only 5. What is the percent of change?

Using Percent of ChangeWhen you know the percent of change,

you can use an equation, or proportion to find the actual amount.

Using Percent of ChangeThe regular price of a portable CD

player at Edwin’s Electronics is $31.99. This week it is on sale for 25% off. Find the amount of the discount. Part (is) = Part %

Original Whole (100%)

x = 25

31.99 100

100x = 799.75 x = 7.9975 ≈ $8

Using Percent of ChangeThe regular price of a portable CD

player at Edwin’s Electronics is $31.99. This week it is on sale for 25% off. Now, Find the sale price.

x = 7.9975 ≈ $8

$31.99 - $8.00 = $23.99 The sale price is $23.99

Using Percent of ChangeThe retail price of a pair of shoes is a

98% increase from its wholesale price. If the wholesale price is $12.50, what is the retail price? Part = Part %

Original Whole (100%)

x = 98

12.50 100

100x = 1225 x = $12.25

Using Percent of ChangeThe retail price of a pair of shoes is a

98% increase from its wholesale price. If the wholesale price is $12.50, what is the retail price?

x = $12.25 $12.50 + $12.25 = $24.75 The retail price is $24.75

Using Percent of ChangeThe regular price of a sweater is

$42.99. It is on sale for 20% off. Find the amount of the discount and sale price. Part = Part %

Original Whole (100%)

x = 20

42.99 100

100x = 859.8 x = $8.598 ≈ $8.60

Using Percent of ChangeThe regular price of a sweater is

$42.99. It is on sale for 20% off. Find the amount of the discount and sale price.

x = $8.60 $42.99 - $8.60 = $34.39 The sale price is $34.39

Using Percent of ChangeYour TurnA backpack that usually sells for $39 is

on sale for 33% off. Find the amount of the discount and the sale price.

Using Percent of ChangeYour TurnA sporting good store is having a

closeout on a certain style of running shoes. They are marked 55% off the regular price. Find the amount of the discount and the sale price.

Using Percent of ChangeYour TurnA gallery owner purchased a very old

painting for $3,000. The painting sells at a 325% increase in price. What is the retail price of the painting?