Edexcel IGCSE Math A 1.7 ratio and proportion

Use ratio-and-proportion questions to simplify ratios, share money, scale recipes and calculate unknown quantities from context.

Exam points

Simplify ratios from counts or tables and convert ratio parts into fractions of a total.
Share money or objects in two- and three-part ratios, then adjust the amounts.
Use scale factors in recipes, currencies or populations to calculate unknown quantities.

Covered syllabus points

1.7.A Ratio notation 1.7.B Divide a quantity in a given ratio or ratios Share £416 1.7.C The process of proportionality to evaluate unknown 1.7.D Missing quantities in direct proportion 1.7.E Word problems about ratio and proportion

[Maximum number: 4]

Pau, Sam and Tia share £ 240 in the ratios 3: 4: 5
Sam and Tia each give £ 10 of their share to Pau.
Work out the ratios of the amounts of money that Pau, Sam and Tia now have.
Give your answer in its simplest form.

$240\div(3+4+5)=20$

Initial shares:
60, 80, 100

After Sam and Tia each give Pau £10:
80, 70, 90

Simplified ratio:
8:7:9

Other orders are acceptable if labelled correctly.

[Maximum number: 2]

The table shows the populations of five countries.

Table for Question 1.7 Ratio and proportion question 2 — Edexcel IGCSE Math A Higher

Given that
$\text{population of Fiji}=\frac{1}{k}\times\text{population of Sweden}$

work out the value of k.
Give your answer correct to the nearest whole number.

$k=\ldots$

Working:
$k=\frac{9.9\times10^6}{9.1\times10^5}$

Final answer:
k=11

M1 for the correct division. A1 for 11; allow 10.8 to 11 inclusive. If M1 not scored, B1 for an answer of $\frac{1}{11}$ with 10.8 to 11 allowed for the denominator.

[Maximum number: 3]

Avril bakes a cake.
She uses flour, butter and sugar such that
weight of flour: weight of butter =6: 5
weight of butter: weight of sugar =3: 2
Avril uses 120 grams of sugar.
Work out the weight of flour Avril uses.
grams

Butter:

120\times\frac32=180

Flour:

180\times\frac65=216

Final answer:

216\text{ g}

M1 for finding one share or the amount of butter, or for writing the 3-part ratio correctly.
M1 for a correct calculation or equation to find the amount of flour.
A1 for flour =216, clearly labelled.

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Covered syllabus points

1.7 Ratio and proportion question 1

1.7 Ratio and proportion question 2

1.7 Ratio and proportion question 3