document.write( "Question 954351: rays boat can go 20 mph in still water. how far downstream can ray go if the current is 5mph and he wishes to go down and back in 4 hours. \n" ); document.write( "

Algebra.Com's Answer #583010 by ankor@dixie-net.com(22740) $\"\"$ $\"About$

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rays boat can go 20 mph in still water.
\n" ); document.write( " how far downstream can ray go if the current is 5mph and he wishes to go down and back in 4 hours.
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\n" ); document.write( "20 + 5 = 25 mph effective speed downstream
\n" ); document.write( "20 - 5 = 15 mph effective speed up stream
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\n" ); document.write( "let d = the one-way distance
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\n" ); document.write( "Write a time equation; time = dist/speed
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\n" ); document.write( "time downstr + time upstr = 4 hrs
\n" ); document.write( " $\"d%2F25\"$ + $\"d%2F15\"$ = 4
\n" ); document.write( "multiply by the least common multiple of 25 and 15; 75,resulting in:
\n" ); document.write( "3d + 5d = 75(4)
\n" ); document.write( "8d = 300
\n" ); document.write( "d = 300/8
\n" ); document.write( "d = 37.5 mi downstream, then return
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\n" ); document.write( "Confirm this, find the actual time each way
\n" ); document.write( "37.5/25 = 1.5 hrs
\n" ); document.write( "37.5/15 = 2.5 hrs
\n" ); document.write( "--------------------
\n" ); document.write( "total time: 4 hrs
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