document.write( "Question 800356: A boat can travel 114 miles upstream in the same time that it can travel 186 miles downstream. If the speed of the current is 6 miles per hour, find the speed of the boat without a current. \n" ); document.write( "

Algebra.Com's Answer #483136 by ankor@dixie-net.com(22740) $\"\"$ $\"About$

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A boat can travel 114 miles upstream in the same time that it can travel 186 miles downstream.
\n" ); document.write( " If the speed of the current is 6 miles per hour, find the speed of the boat without a current.
\n" ); document.write( ":
\n" ); document.write( "Let s = boat speed in still water
\n" ); document.write( "then
\n" ); document.write( "(s-6) = effective speed upstream
\n" ); document.write( "and
\n" ); document.write( "(s+6) = effective speed downstream
\n" ); document.write( ":
\n" ); document.write( "Write a time equation, time = dist/speed
\n" ); document.write( "time down = time up
\n" ); document.write( " $\"186%2F%28s%2B6%29\"$ = $\"114%2F%28s-6%29\"$
\n" ); document.write( "Cross multiply
\n" ); document.write( "186(s-6) = 114(s+6)
\n" ); document.write( "186s - 1116 = 114s + 684
\n" ); document.write( "186s - 114s = 1116 + 684
\n" ); document.write( "72s = 1800
\n" ); document.write( "s = 1800/72
\n" ); document.write( "s = 25 mph in still water
\n" ); document.write( ":
\n" ); document.write( ":
\n" ); document.write( "Check this by finding the times each way
\n" ); document.write( "186/31 = 6 hrs
\n" ); document.write( "114/19 = 6 hrs
\n" ); document.write( " \n" ); document.write( "

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