document.write( "Question 805452: A motorboat travels 11 mph in still water. It travels 10 miles upstream and 10 miles downstream in a total of 5.5 hours. What is the speed of the current? \n" ); document.write( "
Algebra.Com's Answer #485277 by mananth(16946)\"\" \"About 
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boat speed = 10 mph
\n" ); document.write( "current speed = x mph
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\n" ); document.write( "against current = 10 - x
\n" ); document.write( "with current = 10 + x
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\n" ); document.write( "Total distance = 11 miles Total Time= 5.50 hours
\n" ); document.write( "Time upstream + time downstream = 5.5 hours
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\n" ); document.write( "11 /( 10 - x )+ 11 /( 10 + x )= 5.5
\n" ); document.write( "11 ( 10 + x )+ 11 ( 10 - x )= 5.50 ( 100 - 1 X^2 )
\n" ); document.write( "110 + 11 x + 110 -11 x = 550 - 5.5 X^2
\n" ); document.write( "220 - -550 = -5.5 X^2
\n" ); document.write( "-330 = -5.5 X^2
\n" ); document.write( "-5.5 X^2= -330
\n" ); document.write( "X^2 = 60
\n" ); document.write( "X = +/- 7.75 Ignore negative value
\n" ); document.write( "current speed = 7.75 mph
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