document.write( "Question 1056912: A motorboat goes downstream in a river and covers the distance between two coastal towns in 5 hours. It covers this distance upstream in 6 hours. If the speed of the stream is 2 km/h, find the speed of the boat in still water. \n" ); document.write( "

Algebra.Com's Answer #671980 by ikleyn(52781) $\"\"$ $\"About$

You can put this solution on YOUR website!
.
\n" ); document.write( "A motorboat goes downstream in a river and covers the distance between two coastal towns in 5 hours.
\n" ); document.write( "It covers this distance upstream in 6 hours. If the speed of the stream is 2 km/h, find the speed of the boat in still water.
\n" ); document.write( "~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "

\r\n" );
document.write( "Let \"u\" be the boat speed in still water, in km/h.\r\n" );
document.write( "\r\n" );
document.write( "Then the boat speed downstream is (u+2) km/h, and the distance downstream is\r\n" );
document.write( "\r\n" );
document.write( "5*(u+2) kilometers.  (The distance = rate*time, as you know).\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "The boat speed upstream is (u-2) km/h, and the distance upstream is \r\n" );
document.write( "\r\n" );
document.write( "6*(u-2) kilometers.\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "Since the distance downstream is the same as upstream, you have this equation\r\n" );
document.write( "\r\n" );
document.write( "5(u+2) = 6(u-2).\r\n" );
document.write( "\r\n" );
document.write( "Simplify and solve it for \"u\". You will get the answer u = 22 km/h.\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "Answer.  The speed of the boat in still water is 22 km/h.\r\n" );
document.write( "

\r
\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "

\n" );