Question

    A motor car travels a distance of 100 km at the speed of

    20 kmph. If it covers the next 140 km of its journey at the speed of 70 kmph and last 60 km of its journey at the speed of 20 kmph. What is the average speed of the car?
    A 30 kmph Correct Answer Incorrect Answer
    B 60 kmph Correct Answer Incorrect Answer
    C 80 kmph Correct Answer Incorrect Answer
    D 40 kmph Correct Answer Incorrect Answer
    E none of these Correct Answer Incorrect Answer

    Solution

    D1= 100 Km, S1= 20 Km/hr, D2= 140 Km, S2 = 70 Km/hr, D3 = 60 Km, S3= 20 km/hr. T1= (Distance )/Speed = (100 )/20 = 5 hr. T2 = (Distance )/Speed = (140 )/70 = 2 hr. T3= (Distance )/Speed = (60 )/20 = 3 hr. Average Speed= (Total Distance )/(Total Time) = (300 )/10 = 30 km/hr.

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