document.write( "Question 252103: Jane took 15 min to drive her boat upstream to water ski. Coming back later, at the same boat speed, took her 5 min. If the current in that part of the river is 10km/hr, what is her boat speed in still water? \n" ); document.write( "

Algebra.Com's Answer #183874 by vksarvepalli(154) $\"\"$ $\"About$

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let the speed of the boat in still water be v km/hr and the one trip distance be d kms\r
\n" ); document.write( "\n" ); document.write( "while upstream the net speed will be (v-10)km/hr
\n" ); document.write( "time taken to drive upstream = d/(v-10) hrs i.e., = 15 min = 1/4 hrs\r
\n" ); document.write( "\n" ); document.write( "and net speed downstream = (v+10)km/hr\r
\n" ); document.write( "\n" ); document.write( "time taken to drive downstream = d/(v+10) hrs = 5 min = 1/12 hrs\r
\n" ); document.write( "\n" ); document.write( "so, d/(v-10)=1/4 and d/(v+10)=1/12\r
\n" ); document.write( "\n" ); document.write( "dividing both the equations\r
\n" ); document.write( "\n" ); document.write( " (v+10)/(v-10) = 3/1\r
\n" ); document.write( "\n" ); document.write( "so v+10=3v-30\r
\n" ); document.write( "\n" ); document.write( "2v=40\r
\n" ); document.write( "\n" ); document.write( "thus v=20\r
\n" ); document.write( "\n" ); document.write( "boat speed in still water=20km/hr Ans. \n" ); document.write( "

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