Section 3.7 percent of change (Algebra)

1. a. What is 20% of 80?

4

b. Why is four wrong?

%

1. a. What is 20% of 80?

1600

c. Why is one thousand six hundred wrong?

%

1. a. Find 20% of 80.

16 or 16.00

d. Why is one fourth right?

80x .20

0016016 00%

2. a. What is 35% of 20?

7.35

b. Why is seven and thirty-five hundredths wrong?

%

2. a. What is 35% of 20?

700

c. Why is seven hundred wrong?

%

2. a. Find 35% of 20.

7 or 7.00

d. Why is seven right?

20x .35

100607.00

3. a. There is a discount of 25% off on a $60 pair of shoes. How much are the shoes?

$25

b. Why is twenty-five dollars wrong?

%


$15

c. Why is fifteen dollars wrong?

%


$45

d. Why is forty-five dollars correct?

$60x .25300

120$15.00

$60- 15$45

4. a. A shirt cost $30 plus 7% tax. What is the total cost?

$37

b. Why is thirty-seven dollars wrong?

%


$2.10

c. Why is two dollars and ten cents incorrect?

%


$32.10

d. Why is thirty-two dollars and ten cents correct?

$30x .07

$2.10

$30.00+ 2.10$32.10

5. a. A $300 bike is on sale. How much is the cost?

$275

b. Why is two hundred seventy-five dollars wrong?

%


$75

c. Why is seventy-five dollars wrong?

%


$225

d. Why is two hundred twenty-five dollars correct?

$300x .25150060

$75.00

$300- 75

$225

A shirt that costs $30 last month, now costs $45. What is the percent of change?

15

c. Why is 15 incorrect?

%

A shirt that costs $30 last month, now costs $45. What is the percent of change?

50%

Why is 1/2 correct?

$45- $30

$15

$15÷ $30

.5 = 1/2

What is the Percent of Change?

Original: 25 New: 30

30 – 25 = 5

5 = 0.2 = 20%

25

What is the percent of change?

1. Original: 55 New: 70



IMPORTANT:

ALWAYS use the DIFFERENCE divide by the ORIGINAL to find the percent of change:

DIFFERENCE

ORIGINAL

Remember to do your Classwork:

Page 162 # 4 – 36 even

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