On a 400 m track, two athletes start together from the start line and run the same way at 5 m/s and 3 m/s. After how many seconds are both at the start line together for the first time?

Question

Accepted Answer

400 s. Lap times are 80 s and 1331/3 s. The first common multiple: 80×5=400=1331/3×3, so 400 s. (200 s is when the faster first laps the slower, not at the start line.)

On a 400 m track, two athletes start together from the start line and run the same way at 5 m/s and 3 m/s. After how many seconds are both at the start line together for the first time?

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