Ratio and Proportion

Chapter 11: Ratio and proportion

Cambridge Lower Secondary Mathematics Book 9
Ms. Siti Masitoh, S.Mat.

Open Ended

What is the definition of Ratio?

Multiple Choice

Which one of the following is the correct definition of ratio?

• A ratio is a comparison of two numbers by division.
• A ratio is a comparison of two numbers by subtraction.
• A ratio is a comparison of two numbers by addition.
• A ratio is a comparison of two numbers by multiplication.

Multiple Select

Choose all the correct statements that describe the relationship between the number of bananas and apples.

• the ratio of apples to bananas is 2 to 3

• the ratio of bananas to apples is 3 to 2

• for every 3 bananas there are 2 apples

• out of 5 pieces of fruit, 2 are apples

• out of 3 pieces of fruit, 2 are apples

Math Response

Simplify these ratios.

1. 8 cm : 4 mm

Note : Answer using slash (/) for example -> if your answer 2:3, write as $$\frac{2}{3}$$

Type answer here

Correct Answer: \frac{20}{1}

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Multiple Choice

A school maths club has 35 members. The ratio of boys to girls is 3 : 4.

1. How many girls and boys are in the club?

• There are 15 boys and 20 girls in the club.
• There are 18 boys and 17 girls in the club.
• There are 10 boys and 25 girls in the club.
• There are 20 boys and 15 girls in the club.

Multiple Choice

1. Six packets of potato chips cost $12. What is the cost of eight packets of potato chips?

• $14
• $16
• $18
• $20

11.1 Using Ratio


11.2 Direct and Invers Proportion

-> use ratios in a range of contexts.




-> understand the relationship between two quantities when they are in direct or inverse proportion.

​Answer

a. 1 part is worth 500 ÷ 2 = 250 mL 

mango juice: 3 × 250 = 750 mL

​Answer

b. Total: 500 + 750 = 1250 mL = 1.25 L

Cherries: 2 parts = 80 g,
so 1 part =

Sultanas: 5 parts =

Answer

To make a cake, Marco uses sultanas and cherries in the ratio 5 : 2.

Marco uses 80 g of cherries to make the cake.

What mass of sultanas does Marco use?

Question

Let's do this together.

Math Response

A fruit dessert contains raspberries and strawberries in the ratio 1 : 2. There are 400 g of strawberries in the dessert.

How many grams of raspberries are there in the dessert?

Type answer here

Correct Answer: 200

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Math Response

A fruit dessert contains raspberries and strawberries in the ratio 1 : 2. There are 400 g of strawberries in the dessert.

How much fruit is there altogether in the dessert?

Type answer here

Correct Answer: 600

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