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primary 6 | Maths
| Ratio
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Date Posted: 5 years ago
Views: 634
The number of boys before and after the 84 girls left were the same.
Before the 84 girls left, the ratio of boys to girls were 3 : 5.
After the 84 girls left, the ratio of boys to girls were 2 : 1
Since the number of boys were the same, we can combine the 2 ratios together:
So before, the ratio was 6 : 10.
After, the ratio was 6 : 3
The decrease by 7 units must be from the 84 girls.
7u = 84
u = 12
Hence, the number of girls at the start was 10u, which is 120.
Before the 84 girls left, the ratio of boys to girls were 3 : 5.
After the 84 girls left, the ratio of boys to girls were 2 : 1
Since the number of boys were the same, we can combine the 2 ratios together:
So before, the ratio was 6 : 10.
After, the ratio was 6 : 3
The decrease by 7 units must be from the 84 girls.
7u = 84
u = 12
Hence, the number of girls at the start was 10u, which is 120.
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Boys : Girls
3 : 5
2 : 1
No boys left so, we combine the two ratios
3 x 2 = 6 (common multiples)
5 x 2 = 10
Ratio before any girl left - 6 : 10
2 x 3 = 6
1 x 3 = 3
Ratio after the girls left - 6 : 3
10 - 3 = 7
7 units represent the 84 girls who left
1 unit - 84 / 7 = 12
10 units (total amount of girls) - 12 x 10 = 120
3 : 5
2 : 1
No boys left so, we combine the two ratios
3 x 2 = 6 (common multiples)
5 x 2 = 10
Ratio before any girl left - 6 : 10
2 x 3 = 6
1 x 3 = 3
Ratio after the girls left - 6 : 3
10 - 3 = 7
7 units represent the 84 girls who left
1 unit - 84 / 7 = 12
10 units (total amount of girls) - 12 x 10 = 120
Date Posted:
5 years ago
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