At a school fund-raising fair, Priya sold blue and yellow star stickers. Each blue sticker was sold for 40 cents and each yellow sticker for 70 cents. Priya sold 5 more yellow stickers than blue stickers. In total, she collected $20.00 from the sale of the stickers.
- How many stickers did Priya sell altogether? (2 marks)
- How much money did Priya collect from the blue stickers? (2 marks)
Need a hint?
Make equal-length bars for the blue and yellow stickers. Keep the 5 extra yellow stickers in a separate bar before finding the value of each pair.
Worked answer
- Convert $20.00 to 2000 cents.
- Each blue-yellow pair is worth 40 + 70 = 110 cents.
- The 5 extra yellow stickers are worth 5 × 70 = 350 cents.
- The equal pairs are worth 2000 − 350 = 1650 cents.
- 1650 ÷ 110 = 15, so there are 15 blue stickers and 15 + 5 = 20 yellow stickers.
- Priya sold 15 + 20 = 35 stickers altogether.
- The blue stickers brought in 15 × 40 = 600 cents = $6.00.
The mistake this question tests
Converting units (kg, ℓ, m, cm³)
Do not divide the total amount by 110 cents straight away. The 5 extra yellow stickers must first be valued separately at 70 cents each.
How to fix it at home →Wrong answers children often give:
- $14.00 Calculation slip
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