Problem 12 · 2020 Math Kangaroo
Medium
Geometry & Measurement
spatial-reasoning
Luana builds a fence using pieces of wood 2 metres long and half a metre wide, all the same shape. The picture shows the finished fence. How long is the fence, in metres?
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Answer: B — 6.5
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Hint 1 of 2
Each board is 2 m long, but where boards overlap, length is shared, not doubled.
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Hint 2 of 2
Add the board lengths along the fence, subtracting the overlaps.
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Approach: add board lengths along the fence, accounting for overlaps
- The fence is made of 2 m boards whose ends overlap as shown in the picture.
- Adding the lengths along the run, with the shared overlaps counted once, the total length is 6.5 m.
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