document.write( "Question 989697: Traveling at full speed on a river, it takes 2 hours for a motorboat to travel 8 miles downstream and 4 miles back upstream. If the current's speed is 2mph, what is the maximum speed of the boat in still water? \n" ); document.write( "

Algebra.Com's Answer #609931 by MathTherapy(10552) $\"\"$ $\"About$

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\n" ); document.write( "\n" ); document.write( "Traveling at full speed on a river, it takes 2 hours for a motorboat to travel 8 miles downstream and 4 miles back upstream. If the current's speed is 2mph, what is the maximum speed of the boat in still water?
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Let speed of boat in still water be S
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document.write( "Total speed when travelling downstream: S + 2
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document.write( "Total speed when travelling upstream: S - 2
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document.write( "We can then form the following TIME equation: 
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document.write( "8(S - 2) + 4(S + 2) = 2(S + 2)(S - 2) -------- Multiplying by LCD, (S + 2)(S - 2)
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document.write( "(S - 8)(S + 2) = 0
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document.write( "S, or speed in still water =  mph    OR    S = - 2 (ignore) \n" );
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