2. How many ants compare to spider?
Ants : Spiders = 7 : 4 or
7
4
3. The Concept Of Ratio Of
Two Quantities
Learning Outcomes
State whether two pairs of quantities are a
proportion.
Determine if a quantity is proportional to
another quantity
Simplify ratio
4. A Ratio is a comparison of two
quantities 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
6. Example
Write 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
=
7. Example
Write 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
=
8. Do you like chocolate?
Ali and Ahmad also like chocolate !!!!
9. 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
10. 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
11. Activity
a) 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?
12. The ratio of the number of apples to
oranges John had is 3:8. If there are 40
oranges, how many apples are there?
A
O
40 ÷ 8 = 5
5 × 3 = 15
13. 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
a
d
c
b
a
d
c
2
1
2
1
4
2
4
2
5
3
7
2
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