Problem 8 · 2015 Math Kangaroo
Easy
Counting & Probability
careful-counting
In the diagram you can see a very ragged island. Some of the frogs are sitting in the water. How many are sitting on the island?
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Answer: B — 6
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Hint 1 of 2
The wavy line is the edge of the island; some frogs are inside it on land and some outside it in the water.
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Hint 2 of 2
Point at each frog and ask: is it inside the wavy line or out in the water?
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Approach: count only the frogs sitting inside the island's edge
- The wavy line is the shore: everything inside it is the island, everything outside is water.
- Go frog by frog and keep only the ones inside the wavy line.
- Counting those, exactly 6 frogs are sitting on the island.
- So the answer is 6.
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