Warm Ups1) Thirty is 12% of what number?

2) Find 115% of 140.

3) Find I, if p = $950, r = 9%, and t = 6 months

Answers:

1) 250

2) 161

3) $42.75

Return Ch. 3 test – questions?

4 - 5 Percent of Change

Objective: To solve percent word problems.

Standard 5.0

Example 1

Find the final price of a pair of $106 jeans if they are discounted 12% (sales tax not included).

Example 2

40% offOriginally $34

How much is the sale price? (percent decrease)

What will the price be after 7% tax?(percent increase)

Soooo…

Discount is subtracted

Tax is added

Always subtract discount then add tax!

Coat: $195.00

Discount: 40%

Sales tax: 5%

How much is the sale price? (percent decrease)

What will the price be after 5% tax? (percent increase)

Example 3

Try with a mathlete

Find the final price of a $55 shirt if it is discounted 15% and the sales tax is 8%.

Answer: $50.49

ZONK

1. What percent of 16 is 5.12?

32%2. What number is 25% of 64?

163. -6 = x + 4

8

-80

ZONK

4. Original: 78 pennies

new: 36 pennies

decrease, 54%

5. Original: $62

new: $98

increase 58%

6. Television: $299

Tax: 4.5%

$312.46

7. Jacket: $64

discount: 30%

tax: 4%

$46.59

HomeworkPercent Word Problems*Read the problem carefully to determine which equation to use!

4 types: Words to look for: Things to know:

is % of “is” and “of” “is” means equal

“of” means times

“what” means variable

% written as decimal

I = prt “interest” I = interest earned ($)

P = Principle ($)

R = interest rate (% to decimal)

T = time (in years)

% increase “increase” or

“sales tax”

New – old = %

old 100

% decrease “decrease” or

“sale”

Old – new = %

old 100

Homework

Pg. 225 #21 – 29 all

Math Lab Warm Ups1) Twenty is 18% of what number?

2) Find 135% of 120.

3) Find I, if p = $1200, r = 7%, and t = 9 months

Example 2

40% offOriginally $34

How much is the sale price? (percent decrease)

What will the price be after 7% tax?(percent increase)