<PRE><B>Question 490841</B>
You row upstream at 5 mph and downstream at 11 mph.
 You row upstream until you get tired and then downstream to your starting point. How far did you row if the entire trip took 4 hours?
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Let d = the one-way dist rowed
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Write a time equation, time = dist/speed
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up time + down time = 4 hrs
{{{d/5}}} + {{{d/11}}} = 4
multiply eq by 55, results
11d + 5d = 55(4)
16d = 220
d = {{{220/16}}}
d = 13.75 distance one way, or total of 2(13.75) = 27.5 miles
:
:
Check your solution by finding the actual time each way
13.75/5 = 2.75 hrs
13.75/11 =1.25 hrs
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total time: 4 hrs</PRE>