On a 400 m circular track, Hina runs at 5 m/s and Sara at 8 m/s, starting together from the same point. After how many seconds will they first be together again at the starting point?
Correct answer C. 400 seconds
Explanation
Hina takes 400 / 5 = 80 s per lap and Sara 400 / 8 = 50 s. They are next at the start together after LCM(80, 50) = 400 seconds.
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