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primary 6 | Maths | Ratio
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primary 6 chevron_right Maths chevron_right Ratio chevron_right Singapore

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Date Posted: 4 months ago
Views: 66
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4 months ago
This is a common difference question

At first, ratio = 3:7
Difference = 7 - 3 = 4

In 10 years, ratio = 11:19
Difference = 19 - 11 = 8


Notice that their age difference will always be the same. So, make the difference of the ratio at first the same as the one after 10 years.

3 : 7 → x2 → 6 : 14
Difference = 4 → x2 = 8

However, 11- 6 = 5
19 - 14 = 5

This is not correct as only difference between future and present is only 5 years. So, we need to multiply by 2.

Ratio at first = 6 : 14 = 12 : 28
Ratio in 10 years time = 11:19 = 22 : 38

Check:
22 - 12 = 10 (correct)
38 - 28 = 10 (correct)

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Phylicia Tong
Phylicia Tong's answer
164 answers (A Helpful Person)
1st
Familiarise yourself with Constant difference, constant total and constant part concepts.