Problem 6 · 2020 Math Kangaroo
Medium
Spatial & Visual Reasoning
foldingpaper-cutting
Paulo took a rectangular sheet of paper, yellow on one side and green on the other, and made the folds shown by the dotted lines to build a little paper plane. To decorate it, he punched one round hole, marked on the last picture. When he unfolded the sheet again, he found several holes in it. How many holes did he count?
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Answer: D — 8
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Hint 1 of 2
One punched hole passes through every layer the paper is folded into at that spot.
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Hint 2 of 2
Count how many layers stack up where the hole is punched.
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Approach: count layers pierced by the single punch
- When the folded plane is punched, the hole goes through all the paper layers stacked there.
- Unfolding spreads those holes out; the layers give 8 holes in total.
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