SOLUTION: Chance paddled a canoe 10 miles upstream in a river that has a current of 4 mph. He then turned around and paddled downstream until he reached his original starting place. If the e
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Question 679635: Chance paddled a canoe 10 miles upstream in a river that has a current of 4 mph. He then turned around and paddled downstream until he reached his original starting place. If the entire trip took him 7 hours, how fast would Chance paddle in still water?
Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
Let = the speed of the boat in still water
= speed of canoe going downstream
= speed of canoe going upstream
Let = time to go upstream
= time to go downstream
------------------
Equation for going upstream:
(1)
Equation for going downstream:
(2)
--------------------------
(1)
and
(2)
(2)
Substitute (1) into (2)
(2)
(2)
Multiply both sides by
(2)
(2)
(2)
Use quadratic formula
The speed in still water is 5.676 mi/hr
check answer:
(1)
(1)
(1)
(1) hrs
-------------------
(2)
(2)
(2)
(2)
----------------
This is pretty close. Error could be
due to rounding off. I think the method
is correct anyway.
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