Subject

    Quantitative Aptitude

    Topic

    Average

    The ratio of speeds of a car, a train and a bus is 5:9:4. The average speed of the car, the bus and the train is 72 km/hr together. What is the average speed of the car and the train together ?

    ক)
    84 km/hr
    খ)
    96 km/hr
    গ)
    72 km/hr
    ঘ)
    60 km/hr

    Explanation

    Let the speeds of the car, train and bus be 5x, 9x and 4x km/hr respectively. Average speed = 5x + 9x + 4x/3 = 18x /3 = 6x km/hr. Also, 6x = 72 => x = 12 km/hr Therefore, the average speed of the car and train together is = 5x+9x2\frac{5x+9x}2 = 7x = 7 ×\times 12 = 84 km/hr

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