Used the breadth multiplied by the height (25 × 30 = 750 cm²) as the base area instead of length × breadth (40 × 25 = 1 000 cm²), giving 3 000 ÷ 750 = 4 cm.
PRIMARY 5 · MATHEMATICS
Volume
Top 5 mistakes
Ranked by how often they appear across 73 MOE-aligned practice questions in our archive.
Halved the length when finding the base area (20 × 25 = 500 cm²) and divided the block volume by this incorrect area: 3 000 ÷ 500 = 6 cm.
Correctly found the rise of 3 cm but then added it to the existing water height of 12 cm, giving the new water level (15 cm) instead of the rise.
Added the three dimensions (8+5+3 = 16) instead of multiplying.
Used only 8×5 = 40, forgetting the height.
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