Priya and Marcus had some stickers each. After Priya gave 14 of her stickers to Marcus, the ratio of Marcus's new number of stickers to Priya's remaining number of stickers is 5 : 2. Find the ratio of the number of stickers Priya had to the number of stickers Marcus had at first.
Need a hint?
After Priya gives away 14, she has 34 left. Use the ratio 5 : 2 to work backwards and find how many stickers each person had at first.
Worked answer
- After giving, Priya has 34 of her stickers left.
- The ratio of Marcus's new stickers to Priya's remaining stickers is 5 : 2.
- Let Priya's remaining stickers be 2 units. Then Marcus's new stickers are 5 units.
- Priya's remaining 2 units is 34 of her original stickers.
- So Priya's original stickers = 2 units × 43 = 83 units.
- Priya gave away 14 × 83 = 23 units to Marcus.
- Marcus's original stickers = 5 units − 23 units = 153 − 23 = 133 units.
- Ratio of Priya's original to Marcus's original = 83 : 133 = 8 : 13.
The mistake this question tests
Stopped at one part in ratio
A common mistake is to think Priya's remaining stickers represent 14 of her original amount instead of 34. This leads to incorrect calculations of the original amounts.
How to fix it at home →Wrong answers children often give:
- 2 : 5 Stopped at one part in ratio
- 8 : 15 Calculation slip
- 3 : 5 Fraction of a remainder
More PSLE ratio questions
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See the answer →Short answer · 2mOn Arun's town map, 3 cm represents 15 km
See the answer →Structured · 4mA box contains red and blue beads
See the answer →MCQ · 2mIn a park, the ratio of the number of trees in Garden P to the number of trees in Garden Q is 3 : 5
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See the answer →Practise PSLE ratio until the mistakes stop.
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