Question

    A train covers a certain distance at a speed of 36 km/h

    and the next same distance with a speed of 45 km/h and the next same distance with a speed of 60 km/h. find the average speed?
    A 12.6 km/hr Correct Answer Incorrect Answer
    B 30 km/hr Correct Answer Incorrect Answer
    C 45 km/hr Correct Answer Incorrect Answer
    D 37.8 km/hr Correct Answer Incorrect Answer
    E 18.9 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 36 x 45 x 60/(36 x 45 + 45 x 60 + 60 x 36) Average speed = 3 x 36 x 45 x 60/(1620 + 2700 + 2160) = 291600/6480 = 45 km/hr

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