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(a) H
Ratio and Fraction
String A
String B
From the model diagram, we say
(a) The ratio of the length of string A to the length of string B is 4 : 7.
(b) The ratio of the length of string B to the length of string Ais 7 : 4.
(c) The length of string A is
I of the length of string B.
(d) The length of string n is
I of the length of string A.
a
4
(e) The length of string A is ;
.e
'
11
of the total length.
(f) The lengthof stringn is I of the total length.
11
ffian*trmp$e#
Janethas 70 storybooksand Lily has 98 storybooks.
(a) Find the ratio of the number of Janet'sstorybooksto the number of Lily's
storybooks.
T
ii
(b) ril
T
fr
I
70:98=5:7
(b) Find the ratio of the number of Lily's storybooksto the number of Janet's
storybooksto the total number of storybooks.
70+98=168
They have 168 storybooksaltogether.
98:70:168=7:5:12
3
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s
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20
Matherhatiae Counte 6A
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Dorene'sstampscome from Singapore,Malaysia and Brunei. The ratio of the.numberof
Singaporestampsto the number of Malaysia stampsis 3 : 4.:The ratio.of the number of
Malaysia stampsto the number of Brunei stampsis 6 : 7
(a) Find the ratio of the number of Singaporestampsto the number of Brunei stamps.
Singaporestamps
Malaysia stamps
Malaysia stamps
Brunei stamps
I
Singaporestamps
Malaysia stamps
Brunei stamps
The ratio of the number of Singaporestampsto the number of Brunei stamps
is9:14.
O) If she has 140 stampsaltogether,how many stampsare from Brunei?
The ratio of the number of Singaporestampsto the number of Malaysia stampsto
the number of Brunei stampsis 9 : 12 : L4.
9+12+14=35
35 units represent140 stamps.
1 unit represents(140 + 35) stamps,or 4 stamps.
14 units represent(14 x 4) stamps,or 56 stamps.
She has 56 Brunei stamps.
Note: In part (a), how do we find the ratio of the number of Singaporestampsto the
number of Brunei stampsin general?
Singaporestamps:Malaysiastamps=3;4
Malaysiastamps: Brunei stamps= 6 ;7
Ratio
'21
We must find a common multiple of 4 and 6 to changethe ratios.
M u l t i p l e so f 4 : 4 , 8 , 1 2 , 1 6
M u l t i p l e so f 6 : 6 , 1 2 , 1 8
12 is the least common multiple of 4 and 6.
Singaporestamps: Malaysia stamps= 3 : 4 = 9 : 12
Malaysiastamps: Brunei stamps= 6 ;7 = 12: 14
Singaporestamps:Brunei stamps=9: 14
Write each of the following ratios in its simplestform.
1 . 1 2 54
2. 45: 120
3. 77 1 2 I
4. 72:162
5 . 1 5 4 0: 7 5
6. 96 : 6 0 :84
7. 75 9 0 : 4 5
8 . 1 4 4: 7 2 : 4 8
9. 96 1 5 6: 7 2
1 0 .7 5 : 5 0 : I 7 5
22
Mathematica Counts 6A