J's answer to Luana's Primary 5 Maths Percentage Singapore question.
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Diagram/model representation :
All Books : ⬛⬛⬛⬛⬛⬛⬛
All Magazines : ⬜⬜⬜⬜⬜
Total = 132
English books : ⬛⬛⬛⬛⬛
English magazines : ⬜⬜⬜
Total for English = 92
Non-English books : ⬛⬛
Non-English magazines : ⬜⬜
Total for non-English = 132 - 92 = 40
So ⬛⬛ + ⬜⬜ = 40
Then ⬛ + ⬜ = 40 ÷ 2 = 20
Then ⬛⬛⬛⬛⬛ + ⬜⬜⬜⬜⬜ = 20 x 5 = 100
From above we know
⬛⬛⬛⬛⬛⬛⬛ +⬜⬜⬜⬜⬜ = 132
⬛⬛⬛⬛⬛ + ⬜⬜⬜⬜⬜ + ⬛⬛ = 132
100 + ⬛⬛ = 132
So ⬛⬛ = 132 - 100 = 32
⬛ = 32 ÷ 2 = 16
⬜ = 20 - 16 = 4
a) all books = 7 × ⬛ = 7 × 16 = 112
b) English magazines = 3 × ⬜ = 3 x 4 = 12
All Books : ⬛⬛⬛⬛⬛⬛⬛
All Magazines : ⬜⬜⬜⬜⬜
Total = 132
English books : ⬛⬛⬛⬛⬛
English magazines : ⬜⬜⬜
Total for English = 92
Non-English books : ⬛⬛
Non-English magazines : ⬜⬜
Total for non-English = 132 - 92 = 40
So ⬛⬛ + ⬜⬜ = 40
Then ⬛ + ⬜ = 40 ÷ 2 = 20
Then ⬛⬛⬛⬛⬛ + ⬜⬜⬜⬜⬜ = 20 x 5 = 100
From above we know
⬛⬛⬛⬛⬛⬛⬛ +⬜⬜⬜⬜⬜ = 132
⬛⬛⬛⬛⬛ + ⬜⬜⬜⬜⬜ + ⬛⬛ = 132
100 + ⬛⬛ = 132
So ⬛⬛ = 132 - 100 = 32
⬛ = 32 ÷ 2 = 16
⬜ = 20 - 16 = 4
a) all books = 7 × ⬛ = 7 × 16 = 112
b) English magazines = 3 × ⬜ = 3 x 4 = 12
Date Posted:
4 years ago
This is the method taught and accepted in primary school. Of course if student understand and able to use algebra method to solve, mark will be granted as well. i understand some GEP student been taught of algebra method.
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