Andrew Pung's answer to Keerthi's Primary 6 Maths Singapore question.
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Let there be 5 units of marbles originally.
Therefore there were 6 units of blue marbles minus 40 originally.
This means that after red marbles were added, because the ratio of blue to red marbles is 2:3, there were 9 units minus 60 red marbles.
However, taking away the added red marbles, this means there was originally 9 units minus 120 red marbles. Because we said there were 5 units of red marbles above, we know 9u-120=5u. This means 4 units is equal to 120, and one unit is equal to 30.
Therefore, there were originally 5u of red marbles which is equal to 150, and 6u-40 blue marbles which is equal to 140. Therefore the difference in number of marbles is 10.
Ans: 10
Therefore there were 6 units of blue marbles minus 40 originally.
This means that after red marbles were added, because the ratio of blue to red marbles is 2:3, there were 9 units minus 60 red marbles.
However, taking away the added red marbles, this means there was originally 9 units minus 120 red marbles. Because we said there were 5 units of red marbles above, we know 9u-120=5u. This means 4 units is equal to 120, and one unit is equal to 30.
Therefore, there were originally 5u of red marbles which is equal to 150, and 6u-40 blue marbles which is equal to 140. Therefore the difference in number of marbles is 10.
Ans: 10
Date Posted:
1 year ago
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