Question

    ST

    A motor-cycle covers 110 km with a speed of 45 km/hr.

    find the speed of the motor-cycle for the next 110 km journey so that the average speed of the whole journey will be 60 km/hr.
    A 117 km/hr Correct Answer Incorrect Answer
    B 150 km/hr Correct Answer Incorrect Answer
    C 120 km/hr Correct Answer Incorrect Answer
    D 88 km/hr Correct Answer Incorrect Answer
    E 90 km/hr Correct Answer Incorrect Answer

    Solution

    Average speed of whole journey = 60 km/hr Using the formula, average speed = 2xy/(x + y) x = speed of first 110 km = 45 km/hr 60 = 2 x (45 times x y)/(45 + y) = 90 km/hr

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