Problem 8 · 2017 Math Kangaroo
Easy
Spatial & Visual Reasoning
foldingpaper-cutting
Bob folds a piece of paper, then punches a hole in it and unfolds it again. The unfolded paper then looks like the picture. Along which dotted line did Bob fold the paper?
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Answer: D
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Hint 1 of 2
Unfolding mirrors the punched holes across each fold line, so the holes are symmetric about that line.
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Hint 2 of 2
Find the line that the four-hole pattern is symmetric across — that was the fold.
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Approach: match the hole pattern's symmetry to the fold line
- A punch through folded paper leaves holes that are mirror images across the fold crease.
- Look at the four holes in the unfolded sheet and find the line they are symmetric about.
- The holes balance across the diagonal shown in (D).
- So Bob folded along that diagonal.
Mark:
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