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    Question

    A man takes 3.5 hours to reach a

    friend's house, which is 50 km away from his residence. He returns home traveling at 20 km/h. Calculate the average speed of the entire trip.
    A 12.67 km/h Correct Answer Incorrect Answer
    B 27.67 km/h Correct Answer Incorrect Answer
    C 16.67 km/h Correct Answer Incorrect Answer
    D None of these Correct Answer Incorrect Answer

    Solution

    ATQ,

    Time taken to return to his residence = (50/20) = 2.5 hours Total distance = 2 × 50 = 100 km Total time = 3.5 + 2.5 = 6 hours Average speed = (100/6) = 16.67 km/h

    Alternate Solution: Speed while going to the friend’s house = (50/3.5) = 14.29 km/h Required average speed = {(2 × 14.29 × 20)/(14.29 + 20)} = (571.6/34.29) = 16.67 km/h

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