Page 138 - Cambridge+Checkpoint+Mathematics+Coursebook+9

14.1 Comparing and using ratios

2 Angelica mixes a fruit drink using mango juice and orange juice in the ratio 2 : 5.
Shani mixes a fruit drink using mango juice and orange juice in the ratio 5 : 11.
a Write each ratio in the form 1 : n.
b Whose fruit drink has the higher proportion of orange juice?

3 In the Seals swimming club there are 13 girls and 18 boys.
a Write the ratio of girls : boys in the form 1 : n.
In the Sharks swimming club there are 17 girls and 23 boys.
b Write the ratio of girls : boys in the form 1 : n.
c Which swimming club has the higher proportion of boys?
4 When Marco makes a cake he uses sultanas and cherries in the ratio 5 : 2.
Marco used 80 g of cherries when he made a cake last week.
What mass of sultanas did he use?
5 When Jerry makes concrete he uses cement, sand and gravel in the ratio 1 : 2 : 4.
For one job he used 15 kg of sand.
a How much cement and gravel did he use?
b What is the total mass of the concrete he made?

6 The table shows the child-to-staff Age of children Child : staff ratios Number of children
ratios in a kindergarten. It also
shows the number of children in up to 18 months 3 : 1 10
each age group.
At the kindergarten there are four 18 months up to 3 years 4 : 1 18
rooms, one for each age group in
the table. 3 years up to 5 years 8 : 1 15
What is the total number of staff 5 years up to 7 years 14 : 1 24
that are needed to look after the
children in this kindergarten?

7 This is part of Hassan’s homework.
Use Hassan’s method to check Question Red gold is made from gold
your answers to the questions below. and copper in the ratio 3 : 1.
a Purple gold is made from gold A red gold necklace has a
and aluminium in the ratio 4 : 1. mass of 56 g.
A purple gold bracelet has a mass
of 65 g. What is the mass of the gold
What is the mass of the aluminium in the necklace?
in the necklace? Answer 3 + 1 = 4 parts
b Pink gold is made from silver, 56 8 4 = 14 g per part
copper and gold in the ratio 1 : 4 : 15. Mass of gold = 3 × 14 = 42 g
A pink gold necklace has a mass Check: copper = 1 × 14 = 14 g,
of 80 g. so total = 42 + 14 = 56 g 9
What is the mass of the copper in
the necklace?
c White gold is made from gold, palladium, nickel and zinc in the ratio 15 : 2 : 2 : 1.
A white gold ring has a mass of 12 g.
What is the mass of the gold in the ring?

14 Ratio and proportion 137