Problem 17 · 2021 Math Kangaroo
Stretch
Logic & Word Problems
caseworkwork-backward
Eva has 5 stickers: a triangle, a circle, a star, a flower and an apple. She sticks one of them on each of the 5 squares of this board so that the star is not on square 5, the apple is on square 1, and the flower is next to both the circle and the triangle. On which square did Eva stick the flower?
| 1 | 2 | 3 | 4 | 5 |
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Answer: D — 4
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Hint 1 of 2
Pin down the sure clues first: the apple goes on square 1, and the star may not go on square 5.
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Hint 2 of 2
The flower touches both the circle and the triangle, so those three stickers sit in a row of three squares with the flower in the middle.
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Approach: place the forced stickers, then fit the flower
- The apple is on square 1, so the circle, star, flower and triangle fill squares 2, 3, 4, 5.
- The flower touches both the circle and the triangle, so circle–flower–triangle sit in three squares in a row with the flower in the middle — either 2–3–4 or 3–4–5.
- If they took 2–3–4, the star would be forced onto square 5, which is not allowed; so they take 3–4–5 and the star goes on square 2.
- That puts the flower on square 4 (D).
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