Question 619027: A tugboat goes 100 miles upstream in 10 hours. The return trip takes 5 hours. Find the speed of the tugboat without a current and the speed of the current.
Answer by ankor@dixie-net.com(22740)   (Show Source):
You can put this solution on YOUR website! A tugboat goes 100 miles upstream in 10 hours. The return trip takes 5 hours. Find the speed of the tugboat without a current and the speed of the current.
:
let s = speed in still water
Let c = speed of the current
then
(s-c) = effective speed upstream
and
(s+c) = effective speed downstream
:
Write distance equation for each way. (dist = time * speed
10(s-c) = 100
5(s+c) = 100
Simplify both equations, divide the 1st equation by 10, divide the 2nd equation by 5, results:
s - c = 10
s + c = 20
-----------Adding eliminates c find s
2s = 30
s = 30/2
s = 15 mph boat speed in still water
:
You can find the current, check the solutions in the original equations
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