Three runners start together from the same point on a 900 m circular track at 3 m/s, 5 m/s and 6 m/s. After how many minutes will all three first be together at the starting point?
Correct answer D. 15 minutes
Explanation
Lap times are 300 s, 180 s and 150 s. They are together at the start after LCM(300, 180, 150) = 900 seconds = 15 minutes.
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