Ratioform2 131006140714-phpapp01

FORM 2

How many ants compare to spider?

Ants : Spiders = 7 : 4 or

7

4

The Concept Of Ratio Of Two QuantitiesLearning Outcomes

State whether two pairs of quantities are a proportion.

Determine if a quantity is proportional to another quantity

Simplify ratio

A Ratio is a comparison of twoquantities of the same kind.

The ratio of X to Y is written as

X : Y or

Example : The ratio of 6 flies to 7

flies is written as 6 : 7 or

Y

X

7

6

Basic Ratio Model

The ratio of A : B is 5 : 7

A

B

2 : 3

2 : 3

ExampleWrite the ratios in the form of a : b or

b

a

Ratio a : b

Eg: 15 : 20 15 : 20 = 3 : 4

12 : 36

RM 5 : 60 sen

28 min : 1 hour

b

a

20

15

4

3=

ExampleWrite the ratios in the form of a : b or

b

a

Ratio a : b

Eg : 15 : 20 15 : 20 = 3 : 4 =

12 : 36

RM 5 : 60 sen =

28 min : 1 hour =

b

a

20

15

4

3

36

12

3

1

60

500

3

25

60

28

15

7

12 : 36 = 1 : 3

500 sen : 60 sen = 25 : 3

28 min : 60 min = 7 : 15

=

Do you like chocolate?

Ali and Ahmad also like chocolate !!!!

Ali and Ahmad have two bars of chocolate of the same size respectively. Ahmad eat 1 out of the 4

slices. Ali eat 2 out of the 8 slices.

1 2 3 4 5 6 7 8

1 2 3 4

Ahmad’s chocolate

Ali’s chocolate

What is the ratio of chocolate that Ahmad eat to the whole ?

What is the ratio of chocolate that Ali eat to the whole ?

Do they eat the same amount of chocolate?

1 : 4

2 : 8

Since both of them ate the same amount, therefore, the ratios 1 : 4 and 2 : 8

are equivalent.

1 : 4

2 ÷ 2 : 8 ÷ 2

2 : 8

2 : 8

1 × 2 : 4 × 2

1 : 4

Activitya) The total value of one of the items is given. The ratio of the number of apples to oranges John had is 3:8. If there

are 15 apples, how many oranges are there?

The ratio of the number of apples to oranges John had is 3:8. If there are 40 oranges, how many apples are there?

AO

40 ÷ 8 = 5

5 × 3 = 15

Work in Group

Ratio Equivalent Ratio

Proportion Cross multiplication

Cross multiplication

= a x d b x c

= 1 x 4 = 4 2 x 2 = 4

b

ad

c

b

ad

c

2

1

2

1

4

2

4

2

5

3

7

2

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