Question

    MT

    A motor-cycle covers 60 km with a speed of 20 km/hr.

    find the speed of the motor-cycle for the next 60 km journey so that the average speed of the whole journey will be 30 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
    E 90 km/hr Correct Answer Incorrect Answer

    Solution

    Average speed of whole journey = 30 km/hr Using the formula, average speed = 2xy/(x + y) x = speed of first 60 km = 20 km/hr 30 = 2 x (20 x y)/(20 + y) = 140 km/hr

    Practice Next