Question 589485
On a canoe trip, Rita paddled upstream (against the current) at an average speed of 2mph relative to the riverbank.
On the return trip downstream (with the current), her average speed was 3mph.
 Find her speed in still water and the speed of the river's current.
:
Let s = speed in still water
let c = speed of the river current
then
(s-c) = effective speed against the current
(s+c) = effective speed with the current
:
We have two effective speed equations,
s - c = 2
s + c = 3
------------adding eliminates c, find s
2s + 0 = 5
s = 5/2
s = 2.5 mph is the speed in still water
:
then using the "with" equation
2.5 + c = 3
c = 3 - 2.5
c = .5 mph is the speed of the current
;
;
You can confirm this in the "against" equation
2.5 - .5 = 2
:
I tried to make this understandable to you. Did I succeed?