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    Question

    Ram makes four trips of equal distances. His speed on

    first trip was 120 km/hr and in each subsequent trip his speed was half of the previous trip. What is the average speed of Ram in these four trips?
    A 12 km/hr Correct Answer Incorrect Answer
    B 16 km/hr Correct Answer Incorrect Answer
    C 64 km/hr Correct Answer Incorrect Answer
    D 32 km/hr Correct Answer Incorrect Answer

    Solution

    Let us assume the distance on the first trip is d The total distance = 4d The speed on first trip = 120 km/h The speed on second trip = 60 km/h The speed on the third trip = 30 km/h The speed on the fourth trip = 15 km/h The total time is taken by Ram in the whole trip = [(d/120) + (d/60) + (d/30) + (d/15) + (15d/120)] = (d/8) The average speed = (4d/d)/(d/8) = 32 km/hr

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