Name
LESSON
Date
Class
Practice C
6-6 Percent of Change
Find each percent of change or amount of change. Round
answers to the nearest tenth, if necessary.
1. 50 is decreased to 19
2. 25 is increased by 80%
3. 40 is decreased to 33
4. 75 is increased to 200
5. $80 is increased by 125%
6. $14.40 is decreased by 20%
7. 11 is decreased by 10%
8. 5.7 is increased to 7.8
9. 42.6 is increased to 71.2
10. 98 is increased by 85%
11. 145 is decreased to 105
12. 79 is increased to 133
13. 40 is increased by 12.5%
14. 119 is increased to 277
15. 537 is decreased to 289
16. 54 is decreased by 75%
17. The school bought 6 new computers for the computer lab. Each
computer has a retail price of $979. The school received a
discount of 12% on each computer. Find the amount of the
discount and the final price for all 6 computers.
18. Ali paid $85 for an antique clock several years ago. She recently
found that it had increased in value 165%. What is the present
value of the clock?
19. In 1950, there were 40.3 million cars registered in the United
States. In 1990, there were 133.7 million cars registered in the
United States. What was the percent increase of registered cars
from 1950 to 1990?
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51
Holt Mathematics
Practice B
6-6 Percent of Change
Practice A
6-6 Percent of Change
LESSON
LESSON
Find each percent of change. Round answers to the nearest
tenth, if necessary.
Complete the table.
Amount of
Change
Original
Amount
% of Change
1. 20 is decreased to 11
45%
2. 24 is increased to 30
25%
25 17 8
36 24 12
25
24
8 25 32%
12 24 50%
3. 56 is decreased to 14
75%
4. 25 is increased to 100
300%
50 40 10
56 40 16
50
40
10 50 20%
16 40 40%
150%
6. 90 is decreased to 75
16.7%
8. 65 is increased to 144
121.5%
Problem
1.
25 is decreased to 17
2.
24 is increased to 36
3.
50 is decreased to 40
4.
40 is increased to 56
5. 18 is increased to 45
Find each percent of change. Round answers to the nearest
tenth, if necessary.
75%
5. 60 is decreased to 15
7. 12 is increased to 48
300%
9. 60 is decreased to 40
33.3%
75%
90%
10. 80 is increased to 152
90.5%
10. 84 is decreased to 8
52.6%
19.4%
12. 248 is decreased to 200
13. 105 is decreased to 32
69.5%
14. 75 is increased to 350
15. 93 is decreased to 90
3.2%
16. 16 is decreased to 2
366.7%
87.5%
17. A backpack that normally sells for $39 is on sale for 33% off.
Find the amount of the discount and the sale price.
11.1%
12. 72 is decreased to 64
71.4%
11. 95 is increased to 145
40%
8. 100 is decreased to 25
60%
11. 15 is increased to 24
9. 42 is increased to 72
6. 15 is increased to 21
61.9%
7. 126 is decreased to 48
13. The Big Bike Shop has in-line skates on sale for 15% off the
regular price. A pair of in-line skates usually costs $89. Find the
amount of the discount and the sale price.
$12.87; $26.13
18. A sporting goods store is having a closeout on a certain style of
running shoes. They are marked 55% off the regular price. The
regular price is $79.95. Find the amount of the discount and the
sale price.
$13.35; $75.65
14. In 1935, there were 15,295 banks in the United States. In 2003,
there were 9,182 banks. What is the percent of change? Is it a
percent increase or decrease?
$43.97; $35.98
19. 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?
40%; percent decrease
15. A jewelry store is having a going-out-of-business sale. All
merchandise is marked 40% off the regular price. The regular
price of a watch is $59.95. Find the amount of the discount and
the sale price.
$12,750
20. In August, the Simons’ water bill was $48. In September, it was
15% lower. What was the Simons’ water bill in September?
$23.98; $35.97
$40.80
16. Last year, there were 381 students at Woodland Middle School.
This year, there are 419 students. What is the percent of
change? Is it a percent increase or decrease?
10%; percent increase
49
Copyright © by Holt, Rinehart and Winston.
All rights reserved.
Holt Mathematics
Practice C
6-6 Percent of Change
LESSON
Find each percent of change or amount of change. Round
answers to the nearest tenth, if necessary.
1. 50 is decreased to 19
62%
2. 25 is increased by 80%
3. 40 is decreased to 33
17.5%
4. 75 is increased to 200
$100
8. 5.7 is increased to 7.8
9. 42.6 is increased to 71.2
67.1%
10. 98 is increased by 85%
11. 145 is decreased to 105
27.6%
12. 79 is increased to 133
68.4%
14. 119 is increased to 277
132.8%
15. 537 is decreased to 289
Find the percent of change from 28 to 42.
• First, find the amount of the change.
$2.88
1.1
46.2%
amount of increase or decrease
percent of change 100
original amount
166.7%
6. $14.40 is decreased by 20%
5
A change in a quantity is often described as a percent increase or
percent decrease. To calculate a percent increase or decrease, use
this equation.
20
7. 11 is decreased by 10%
13. 40 is increased by 12.5%
36.8%
83.3
16. 54 is decreased by 75%
42 28 14
• What is the original amount?
28
• Use the equation.
14
28
Find each percent of change.
1. 8 is increased to 22
amount of change 22 8 40.5
14
8
original amount
original amount
$225.25
original amount
400
60
340
400 100 85
%
25%
Copyright © by Holt, Rinehart and Winston.
85
%
95%
40%
10. 320 is decreased to 304
200%
Copyright © by Holt, Rinehart and Winston.
All rights reserved.
340
8. 15 is increased to 21
80%
9. 7 is increased to 21
%
6. 140 is increased to 273
7. 30 is decreased to 6
Holt Mathematics
10
4. 400 is decreased to 60
amount of change 400 60 75
5. 64 is decreased to 48
231.8%
100 9
90
125
75
125 100 19. In 1950, there were 40.3 million cars registered in the United
States. In 1990, there were 133.7 million cars registered in the
United States. What was the percent increase of registered cars
from 1950 to 1990?
9
90
100 175 %
3. 125 is increased to 200
amount of change 200 125 18. Ali paid $85 for an antique clock several years ago. She recently
found that it had increased in value 165%. What is the present
value of the clock?
2. 90 is decreased to 81
amount of change 90 81 14
8
original amount
$704.88; $5,169.12
51
100 50%
An increase from 28 to 42 represents a 50% increase.
17. The school bought 6 new computers for the computer lab. Each
computer has a retail price of $979. The school received a
discount of 12% on each computer. Find the amount of the
discount and the final price for all 6 computers.
Copyright © by Holt, Rinehart and Winston.
All rights reserved.
Holt Mathematics
Review for Mastery
6-6 Percent of Change
LESSON
5. $80 is increased by 125%
50
Copyright © by Holt, Rinehart and Winston.
All rights reserved.
5%
52
Holt Mathematics
Holt Mathematics