Question 329661: One day last summer, Jim went kayaking on the Little Susitna River in Alaska. Paddling upstream against the current, he traveled 20 miles in 4 hours. Then he turned around and paddled twice as fast downstream and, with the help of the current, traveled 19 miles in 1 hour. Find the rate of the current.
Thanks!!!
Answer by ankor@dixie-net.com(22740)   (Show Source):
You can put this solution on YOUR website! Paddling upstream against the current, he traveled 20 miles in 4 hours.
Then he turned around and paddled twice as fast downstream and, with the help of the
current, traveled 19 miles in 1 hour.
Find the rate of the current.
:
Let s = normal speed in still water
Let c = rate of the current
:
Find his actual speed going up stream
20/4 = 5 mph upstream
then
(s - c) = 5
s = (c+5)
:
2s = fast speed down stream
:
Write a distance equation for downstream; dist = time * speed
1(2s + c) = 19
2s + c = 19
Replace s with (c+5)
2(c+5) + c = 19
2c + 10 + c = 19
2c + c = 19 = 10
3c = 9
c = 3 mph is the current
:
:
Check solution by finding the speed in still water
s = 3 + 5 = 8 mph
"paddled twice as fast downstream and, with the help of the
current, traveled 19 miles in 1 hour."
2(8) + 3 = 19
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