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2.05 Percentage increase and decrease

Worksheet
Percentage increase
1

Abed wants to increase 1500 by 30\%.

a

Calculate 30\% of 1500 and add the answer to 1500.

b

Calculate 130\% of 1500.

c

Are your answers to (a) and (b) the same?

2
a

Find 40\% of 1300 and add your answer to the original amount of 1300.

b

Calculate 140\% of 1300.

c

Are your answers to (a) and (b) the same? Explain why this is.

3

Tracy wants to increase 80 by 30\%.

a

What single percentage should she multiply 80 by?

b

Explain how you got your percentage in part (a).

4

What percentage should a quantity be multiplied by in order to increase the quantity by:

a
3\%
b
112\%
c
48\%
d

24.8\%

e
17\%
f
5\%
g
40\%
h
9.4\%
i
33\%
j
127\%
k
38\%
l
212\%
5

What decimal should a quantity be multiplied by in order to increase the quantity by:

a

9\%

b

33\%

c

7.7\%

d

154\%

6

Increase:

a

80 by 5\%.

b

120 by 10\%.

c

72 by 40\%.

d

320 by 25\%.

e

\$140 by 9\%.

f

\$30\,000 by 20\%.

g

80\text{ km} by 15\%.

h

400\text{ mL} by 35\%.

7

Evaluate the following using a single percentage:

a

Increase 80 by 60\%

b

Increase 400 by 45\%

c

Increase 900 by 8\%

d

Increase 80 by 40\%

e

Increase 1200 by 45\%

f

Increase 1200 by 8\%

Percentage decrease
8
a

Find 15\% of 1500 and subtract your answer from the original amount of 1500.

b

Calculate 85\% of 1500.

c

Are your answers to (a) and (b) the same? Explain why this is.

9

Derek wants to decrease 120 by 70\%.

a

What single percentage should he multiply 120 by?

b

Explain how you got your percentage in part (a).

10

What percentage should a quantity be multiplied by in order to decrease the quantity by:

a
5\%
b
57\%
c
10\%
d
20.7\%
e

75\%

f

15.7\%

g
17\%
h
40\%
i
9\%
j
32\%
k
52\%
l
38\%
11

What decimal should a quantity be multiplied in order to decrease it by:

a

9\%

b

43\%

c

26\%

d

94\%

12

Decrease:

a

70 by 8\%.

b

260 by 10\%.

c

96 by 60\%.

d

250 by 20\%.

e

\$480 by 18\%.

f

\$55\,000 by 45\%.

g

200\text{ km} by 22\%.

h

650\text{ mL} by 30\%.

13

Evaluate the following using a single percentage:

a

Decrease 80 by 60\%

b

Decrease 400 by 45\%

c

Decrease 900 by 8\%

d

Decrease 80 by 40\%

e

Decrease 1200 by 45\%

f

Decrease 1200 by 8\%

Applications
14

A bag of potatoes weighs 50\text{ kg}. When more potatoes are added, the weight of the bag increases by 35\%.

a

Find the percentage that should be multiplied to the weight of the bag to increase it by 35\%.

b

Find the new weight of the bag of potatoes.

15

A bag of rice weighs 120 \text{ kg}. The company who makes these bags decides to increase their weight by 45\%.

a

Find the percentage that should be multiplied to the weight of the bag to increase it by 45\%.

b

Find the new weight of the bag of rice.

16

A bag of rice weighs 110\text{ kg}. When some rice is poured out, the weight of the bag decreases by 40\%.

a

Find the percentage that should be multiplied to the weight of the bag to decrease it by 40\%.

b

Find the new weight of the bag of rice.

17

Steph is going to buy a dress that is marked as 75\% off. The original price was \$36.

a

Find the discount amount.

b

Find the discounted price that Steph will pay for the dress.

18

Duncan is going to buy a hat that is marked as 25\% off. The original price was \$30.

a

Find the discount amount.

b

Find the discounted price that Duncan will pay for the hat.

19

A tennis racket marked at a price of \$90 is advertised to be selling at 45\% off the marked price. Find the discounted price.

20

Very Cheap Auto car company is having a sale such that car prices are discounted by 10\%. If the original price of a car was \$12\,500, find the discounted price of the car.

21

A basket of goods was valued at \$43.70 in January 2011. The inflation rate for the year was 8\%. What is the expected cost of the basket of goods in January 2012?

22

A discus thrower has a personal best of 60 \text{ m}. In their most recent competition, they fall short of their personal best by 30\%. Find the distance of their throw in this competition.

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Outcomes

1.1.3.4

apply percentage increases and decreases in situations, including mark-ups, discounts and GST [complex]

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