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    Question

    A train covers a certain distance at a speed of 20 km/h

    and the next same distance with a speed of 35 km/h and the next same distance with a speed of 60 km/h. find the average speed?
    A 60 km/hr Correct Answer Incorrect Answer
    B 63 km/hr Correct Answer Incorrect Answer
    C 31.5 km/hr Correct Answer Incorrect Answer
    D 75 km/hr Correct Answer Incorrect Answer
    E 90 km/hr Correct Answer Incorrect Answer

    Solution

    Since the distance is same in all the conditions. Therefore, Average speed = 3xyz/(xy + yz + zx) Average speed = 3 x 20 x 35 x 60/(20 x 35 + 35 x 60 + 20 x 60) Average speed = 3 x 20 x 35 x 60/(700 + 2100 + 1200) = 126000/4000 = 31.5 km/hr

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