Cambridge International Mathematics

Topics in arithmetic (Chapter 10) 219

Example 14 Self Tutor

A house is bought forE120 000and soon after is sold forE156 000:What is the

percentage increase on the investment?

percentage change

=

change

original

Method 1: £100%

multiplier

=

new value

old value

=

156 000

120 000

=1: 30

= 130%

) a30%increase occurred

Method 2:

percentage increase

=

increase

original

£100%

=

156 000¡120 000

120 000

£100%

=

36 000

120 000

£100%

= 30%

) a30%increase occurred

EXERCISE 10E.1

1 What multiplier corresponds to a:

a 10%increase b 10%decrease c 33%increase

d 21%decrease e 7 :2%increase f 8 :9%decrease?

2 Use a multiplier to calculate the following:

a increase$80by6% b increase$ 68 by20% c increase 50 kg by14%

d decreaseE 27 by15% e decrease$ 780 by16% f decrease 35 mby10%

3aJason was being paid a wage ofE 25 per hour. His employer agreed to increase his wage by4%.

What is Jason’s new wage per hour?

b At the school athletics day Sadi increased her previous best javelin throw of 29 : 5 mby8%. How

far did she throw the javelin?

c The lawn in Oscar’s back garden is 8 : 7 cm high. When Oscar mows the lawn he reduces its height

by70%. How high is the lawn now?

4 Find the percentage change that occurs when:

a $80increases to$120 b $ 9000 decreases to$ 7200 c E 95 reduces toE 80

d E 90 increases toE 118 e 16 kg increases to 20 kg f 8 m reduces to 6 : 5 m

5 A block of land is bought forE75 000and sold later forE110 000. Calculate the percentage increase in

the investment.

6 A share trader buys a parcel of shares for$4250and sells them for$3800. Calculate the percentage

decrease in the investment.

7 Terry found that after a two week vacation his weight had increased from 85 kg to 91 kg. What

percentage increase in weight was this?

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Y:\HAESE\IGCSE01\IG01_10\219IGCSE01_10.CDR Tuesday, 23 September 2008 3:30:37 PM PETER