Question

    A motor-cycle covers 130 km with a speed of 50 km/hr. find the speed of the motor-cycle for the next 130 km journey so that the average speed of the whole journey will be 75 km/hr.

    A 150 km/hr Correct Answer Incorrect Answer
    B 126 km/hr Correct Answer Incorrect Answer
    C 120 km/hr Correct Answer Incorrect Answer
    D 140 km/hr Correct Answer Incorrect Answer

    Solution

    Average speed of whole journey = 75 km/hr Using the formula, average speed = 2xy/(x + y)  x = speed of first 130 km = 50 km/hr 75 = 2 x (50 x  y)/(50 + y) = 150 km/hr

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