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2025 Math Kangaroo

Problem 12

Problem 12 · 2025 Math Kangaroo Medium
Arithmetic & Operations arithmetic-sequenceoff-by-one

In a 60 m hurdles race there are 5 hurdles. The first hurdle is 12 m after the start, and the distance between any two consecutive hurdles is 8 m. How far is the last hurdle from the finish line?

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Answer: E — 16 m
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Hint 1 of 2
Find the position of the last (5th) hurdle measured from the start.
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Hint 2 of 2
Then subtract that from the 60 m finish line.
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Approach: locate the last hurdle, then measure to the finish
  1. Hurdle 1 is at 12 m and each later hurdle is 8 m further: 12, 20, 28, 36, 44.
  2. The 5th hurdle is at 12 + 4×8 = 44 m.
  3. Distance to the finish = \(60 - 44 = 16\) m, which is (E).
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