Question 790926: jonathan and samantha paddle their canoe 26 miles downstream in 2 hours. after picnic they paddle upstream. after 3 hours they have traveled only 9 miles back. asuming that they padle at a constant rate and the river current is constant, find the speed at which jonathan and samantha can paddle in still water..
Answer by ankor@dixie-net.com(22740)   (Show Source):
You can put this solution on YOUR website! let s = speed in still water
let c = speed of the current
then
(s+c) = effective speed downstream
and
(s-c) - effective speed upstream
:
Write a distance equation of each way; dist = time * speed
:
"paddle their canoe 26 miles downstream in 2 hours."
2(s+c) = 26
:
"they paddle upstream. after 3 hours they have traveled only 9 miles back."
3(s-c) = 9
:
Simplify both equations, divide the first by 2, the 2nd by 3 and you have:
s + c = 13
s - c = 3
-----------Addition eliminates c, find s
2s = 16
s = 8 mph in still water
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