document.write( "Question 818452: A motorboat takes 4 hours to travel 192 km going upstream. The return trip takes 3 hours going down stream. What is the rate of the boat in still water and what is the rate of the current? \n" ); document.write( "

Algebra.Com's Answer #492582 by mananth(16946) $\"\"$ $\"About$

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boat speed =x km/h
\n" ); document.write( "current speed =y km/h
\n" ); document.write( "against current 4 hours
\n" ); document.write( "with current 3 hours
\n" ); document.write( "
\n" ); document.write( "Distance against 192 miles distance with 192 miles
\n" ); document.write( "t=d/r against current -
\n" ); document.write( "192.00 / ( x - y )= 4.00
\n" ); document.write( "4.00 ( x - y ) = 3.00
\n" ); document.write( "4.00 x - 4.00 y = 192.00 ....................1
\n" ); document.write( "
\n" ); document.write( "192.00 / ( x + y )= 3.00
\n" ); document.write( "3.00 ( x + y ) = 192.00
\n" ); document.write( "3.00 x + 3.00 y = 192.00 ...............2
\n" ); document.write( "Multiply (1) by 3.00
\n" ); document.write( "Multiply (2) by 4.00
\n" ); document.write( "we get
\n" ); document.write( "12.00 x + -12.00 y = 576.00
\n" ); document.write( "12.00 x + 12.00 y = 768.00
\n" ); document.write( "24.00 x = 1344.00
\n" ); document.write( "/ 24.00
\n" ); document.write( "x = 56.00 mph
\n" ); document.write( "
\n" ); document.write( "plug value of x in (1) y
\n" ); document.write( "4.00 x -4.00 y = 192.00
\n" ); document.write( "224.00 -4.00 -224.00 = 192.00
\n" ); document.write( "-4.00 y = 192.00
\n" ); document.write( "-4.00 y = -32.00 km/h
\n" ); document.write( " y = 8.00
\n" ); document.write( "boat speed 56.00 km/h
\n" ); document.write( "current speed 8.00 km/h
\n" ); document.write( "
\n" ); document.write( "m.ananth@hotmail.ca
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