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8th Class Mathematics Linear Equations in One Variable Question Bank Linear Equations in One Variable

  • question_answer
    A boat goes downstream and covers the distance between two ports in 4 hours while it covers the same distance upstream in 5 hours. If the speed of the stream is \[2\text{ }kmph,\] what is the speed of the boat in still water?                  

    A)  \[15\text{ }kmph\]                        

    B)                         \[20\text{ }kmph\]                        

    C)                         \[24\text{ }kmph\]                        

    D)                         \[\text{18 }kmph\]

    Correct Answer: D

    Solution :

    Let the speed of the boat in still water be 'x' kmph. The speed downstream \[=(x+2)\,kmph\] The speed upstream \[=(x-2)\,kmph\] We have, \[4(x+2)=5(x-2)\] \[\Rightarrow \]               \[4x+8=5x-10\] \[\Rightarrow \]               \[x=10+8\,\,kmph\] \[\Rightarrow \]               \[x=18\,\,kmph\]


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