Nurul ran a second-hand book stall at a community fair. She sold 360 books before lunch. In the afternoon, she sold 14 of the books that were still on the shelf. At the end, 45% of all the books were unsold. How many books did Nurul sell in the afternoon?
- 90
- 135
- 405
- 540
Need a hint?
After lunch, 34 of the books remaining after the morning sale was left. Use this to find what percentage of the original total remained after the morning sale.
Worked answer
- After selling 14, 34 of the post-morning remainder was left, so that remainder was 45% ÷ 34 = 60% of the total.
- The 360 books sold before lunch were 40% of the total, so 360 ÷ 40% = 900 books.
- Afternoon sales: (900 − 360) ÷ 4 = 135 books.
The mistake this question tests
Fraction of a remainder
A common mistake is to take 14 of the 360 books sold before lunch. The afternoon fraction applies only to the books still on the shelf after the morning sale.
How to fix it at home →Wrong answers children often give:
- 90 Fraction of a remainder
- 405 Calculation slip
- 540 Calculation slip
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See the answer →Practise PSLE percentage until the mistakes stop.
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