Problem 14 · 2019 Math Kangaroo
Medium
Spatial & Visual Reasoning
cube-viewsspatial-reasoning
Each figure is made up of 4 equally big cubes and coloured in. Which figure needs the least amount of colour?
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Answer: B
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Hint 1 of 2
All figures use 4 cubes, so the colour needed depends on how much outside surface shows.
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Hint 2 of 2
The more faces the cubes hide by touching each other, the less surface is left to colour.
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Approach: least colour goes to the most tightly packed figure
- Colour covers every outside face, and a face where two cubes touch is hidden and needs none.
- So the figure whose cubes touch the most hides the most faces and needs the least colour.
- The most tightly packed figure, with the fewest faces showing, is option B.
- So the answer is B.
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