SOLUTION: in still water a boat travels 15 mph. It takes same amount of time to travel 20 miles downstream, with the current, as 10 miles upstream against the current.what is the rate of the

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Question 444914: in still water a boat travels 15 mph. It takes same amount of time to travel 20 miles downstream, with the current, as 10 miles upstream against the current.what is the rate of the waters current?
Answer by htmentor(1343) About Me  (Show Source):
You can put this solution on YOUR website!
Let c = the speed of the current
The 20 mile downstream travel time will be 20/(15+c)
The 10 mile upstream travel time will be 10/(15-c)
Since the times are equal we have
20/(15+c) = 10/(15-c)
Solve for c:
10(15+c) = 20(15-c)
15+c = 30-2c
3c = 15
c = 5
So the rate of the current is 5 mph
Check:
t = 20/(15+5) = 1 hr
t = 10/(15-5) = 1 hr