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    Question

    A train covers a certain distance at a speed of 48 km/h

    and the next same distance with a speed of 60 km/h and the next same distance with a speed of 80 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 48 x 60 x 80/(48 x 60 + 60 x 80 + 48 x 80) Average speed = 3 x 48 x 60 x 80/(2880 + 4800 + 3840) = 691200/11520 = 60 km/hr

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