ZQ Chan's answer to Amanda's Primary 6 Maths Percentage Singapore question.
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Working backwards:
He bought 15 more red counters and caused number of red counters to increase by 20%.
Means that 20% of the original number of red counters = 15.
100% of the original number of red counters = 15 x 5 = 75
Initially, 30% of the total counters were red (the 75 red counters).
Hence to find the number of blue counters (which remained constant):
30% of initial total counters --> 75 counters
10% of initial total counters--> 75 ÷ 3 = 25
70% of initial total counters--> 25 x 7 = 175
Number of blue counters at first = 175
He bought 15 more red counters and caused number of red counters to increase by 20%.
Means that 20% of the original number of red counters = 15.
100% of the original number of red counters = 15 x 5 = 75
Initially, 30% of the total counters were red (the 75 red counters).
Hence to find the number of blue counters (which remained constant):
30% of initial total counters --> 75 counters
10% of initial total counters--> 75 ÷ 3 = 25
70% of initial total counters--> 25 x 7 = 175
Number of blue counters at first = 175
Date Posted:
3 years ago
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