Page 144 - MAT KS3 Y8 Cambridge CheckPoint

14.1 Simplifying ratios

4 Simplify these ratios.
a 600 m : 1 km : 20 m b 75 cm : 1 m : 1.5 m c 300 ml : 2.1 l : 900 ml
d 3.2 kg : 1600 g : 0.8 kg e $1.08 : 90 cents : $9 f 4 cm : 8 mm : 0.2 m
5 Sasha uses this recipe for orange preserve.
Orange preserve
750 g oranges
The ratio of oranges to sugar is 2 : 1. 1.5 kg sugar
juice of one lemon
Is Sasha correct? Explain your answer.

6 This is part of Jake’s homework. Question
Use Jake’s method to simplify these ratios. Simplify these ratios.
a 0.5 : 2 b 1.5 : 3 a 1.5 : 2 b 0.8 : 3.6
c 1.2 : 2.4 d 0.7 : 2.1 Answer
e 3.6 : 0.6 f 7.5 : 1.5 a 1.5 : 2 b 0.8 : 3.6
× 10 × 10
× 10 × 10
15 : 20
8 : 36
g 2.4 : 4 h 1.8 : 6.3 ÷ 5 ÷ 5 ÷ 4 ÷ 4
i 2.1 : 0.7 : 1.4 j 0.03 : 0.15 3 : 4 2 : 9
For questions 7 and 8, work in a group
of three or four.
i Work out the answer to each question by yourself.
ii Compare your answers with the answers given by the other members of your group.
iii Decide which member of the group has given the best answers.
7 Razi and Tanesha are mixing paint.
They mix 250 ml of white paint with 750 ml of red paint and 1.2 litres of yellow paint.

The ratio of white to red to The ratio of white to red to
yellow paint is 1 : 3 : 5. yellow paint is 25 : 75 : 12.

Is either of them correct? Explain your answer.

8 Oditi goes for a run three times a week.
Her notebook shows the time she took
for each run one week. Monday 1 hour 40 mins
a Oditi thinks that the ratio of her times Wednesday 50 mins
for Monday to Wednesday to Friday is
Friday 2½ hours
1 : 2 : 3. Without doing any calculations,
explain how you know that Oditi is wrong. Monday : Wednesday : Friday
b Oditi’s mum uses this method to work
1 hour 40 mins : 50 mins : 2½ hours
1
out the ratio of Oditi’s times.
1.4 : 0.5 : 2.5
Explain the mistakes that Oditi’s mum
has made. × 10 14 : 5 : 25
c Work out the correct ratio of Oditi’s times. ÷ 5 14 : 1 : 5

142 14 Ratio and proportion