What is Percent of Change? Common Examples of Percent of Increase Common 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 Change Percent 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 X = amount of change 100 original amount

Finding Percent of Change 27 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 Change 32 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 Change 20 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 Change 42 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 Change Word 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 Change Word Problems Kelly 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 Change Word Problems: Your Turn Last six weeks Joseph Lawhorn made an 88. This six weeks he made a 92. Please figure the percent of change.

Finding Percent of Change Word Problems: Your Turn Angela 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 Change Word Problems: Your Turn Amber 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 Change When you know the percent of change, you can use an equation, or proportion to find the actual amount.

Using Percent of Change The 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 Change The 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 Change The 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 Change The 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 Change The 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 Change The 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 Change Your Turn A 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 Change Your Turn A 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 Change Your Turn A 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?