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The speed if boat in still …

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The speed if boat in still water is 30 km/hr. it takes the same time for the boat to travel 5 km upstream and 10 km downstream find the speed of the stream.

  • 1 answers

Rashmi Bajpayee 6 years, 11 months ago

Let the speed of the stream be {tex}x{/tex} km/hr.

We know that, Speed = {tex}{{{\rm{Distance}}} \over {{\rm{Time}}}}{/tex}

Speed in upstream = (x -30) Km/h and Speed in downstream =(x + 30) Km/h

Then, Time = {tex}{{{\rm{Distance}}} \over {{\rm{Speed}}}}{/tex}

According to question,

{tex}{5 \over {x - 30}} = {{10} \over {x + 30}}{/tex}

=>          {tex}5\left( {x + 30} \right) = 10\left( {x - 30} \right){/tex}

=>          {tex}5x+150=10x-300{/tex}

=>          {tex}10x-5x=150+300{/tex}

=>          {tex}5x=450{/tex}

=>         {tex}x=90{/tex}

Therefore, the speed of stream is 90 km/hr

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