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9th Class Mathematics Related to Competitive Exam Question Bank Arithmetic

  • question_answer
    If two cars A and B move towards each other, where car A starts at 9 a.m. and car B at 10 a.m. The speeds of the car A and B ar 40 km/hr and 50 km/hr respectively. What distance does car travel when the two cars meet, if the initial distance between A and B is 400 km?

    A)  100 km         

    B)         200 km                

    C)  300 km                

    D)         400 km

    Correct Answer: B

    Solution :

     Let \[t\] hrs. be the time taken by the car \[B\] to reach the crossing point. Hence, \[A\] will take \[(t+1)\] hrs. to reach the same point. Speed of car\[B=50\,\,km/hr\]. Distance covered before the crossing\[=50\times t\] Now, using the strategy (4), we know that the total distance covered by the two cars is the total distance between their starting points. \[i.e.\]  \[40(t+1)+50t=400\] \[\Rightarrow \]               \[40t+50t+40=400\] \[\Rightarrow \]               \[90t=360\] \[\Rightarrow \]               \[t=4\,\,hrs.\] Hence, the distance covered by car                 \[B=50\times 4=200\,\,km\].


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