Question

    On a circular racetrack that measures 4,000 meters in

    circumference, Kia and Sia begin a race at the same point and at the same time, traveling at speeds of 90 km/h and 18 km/h, respectively. If the race continues for 40 minutes, how many times will Kia and Sia meet again at the starting point?
    A 4 Correct Answer Incorrect Answer
    B 3 Correct Answer Incorrect Answer
    C 6 Correct Answer Incorrect Answer
    D 5 Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    Speed of Kia = 90 X (5/18) = 25 m/s Speed of Sia = 18 X (5/18) = 10 m/s Time taken by Kia to complete one round = (4,000/25) = 160 seconds Time taken by Sia to complete one round = (4,000/10) = 400 seconds Time after which both of them will meet at the same starting point = LCM of 160 and 400 = 800 seconds Therefore, number of times they meet in 40 minutes = (40 X 60) ÷ 800 = 3

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