Problem 8 · 2010 Math Kangaroo
Medium
Spatial & Visual Reasoning
paper-cuttingnet-folding
Lines are drawn on a piece of paper and some of the lines are numbered. The paper is cut along some of these lines and then folded into the shape shown. Along which lines were the cuts made?
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Answer: B — 2, 4, 6, 8
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Hint 1 of 2
A fold keeps the paper joined, but a cut lets a flap lift up and stand free.
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Hint 2 of 2
Match each free-standing flap in the folded picture back to its numbered line on the flat sheet.
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Approach: unfold the model in your head
- On the flat sheet, a fold-line stays attached but a cut-line frees a flap to be raised.
- Tracing the flaps that lift up in the folded picture back to the sheet, they sit on the even-numbered lines.
- So the cuts were made along lines 2, 4, 6 and 8 (answer B).
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