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    Question

    From a point on a circular track 10 km long A, B and C

    started running in the same direction at the same time with speeds of 3(1/3) km/h, 5 km/h and 2 km/h respectively. Then on the starting point all three will meet again after
    A 30 hours Correct Answer Incorrect Answer
    B 20 hours Correct Answer Incorrect Answer
    C 10 hours Correct Answer Incorrect Answer
    D 15 hours Correct Answer Incorrect Answer

    Solution

    ∵ Total time taken = Total distance/Average speed ∴ Time taken by A to complete one round =10/3(1/3) = 3 hours = 3 × 60 mins = 180 minutes ∴ Time taken by B to complete one round =10/5 hours = 10/5 × 60 mins = 120 minutes ∴ Time taken by C to complete one round = 10/2 hours = 10/2 × 60 mins = 300 minutes ∴ Time taken by all three to meet again at the starting point = LCM of 180, 120 and 300 minutes = 600 minutes = 1800/60 hours = 30 hours

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