Problem 13 · 2025 Math Kangaroo
Hard
Ratios, Rates & Proportions
distance-speed-time
Five swimmers from a school are training for a relay race. The five participants swim the same distance, one after the other, without stopping. The coach stops the intermediate time after each swimmer. The first swimmer takes 2 minutes and 8 seconds. The stopwatches show the total time after the first, second, third, fourth and fifth swimmer (see picture). Which swimmer swam the distance the fastest?
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Answer: D — the fourth
Show hints
Hint 1 of 2
Each stopwatch shows the total time after that many swimmers, so subtract to get each leg.
Still stuck? Show hint 2 →
Hint 2 of 2
All swam the same distance, so the fastest is the one with the shortest individual leg.
Show solution
Approach: difference of consecutive total times
- The watches show running totals: 2:08, 4:07, 6:10, 8:05, 10:03.
- Subtract each total from the one before to get each swimmer’s own time: 128 s, 119 s, 123 s, 115 s, 118 s.
- Same distance means fastest = shortest time, and 115 s is the smallest.
- So the fourth swimmer was fastest.
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