Question 872026: A boat can travel 20 miles downstream in 2 hours. The same boat can travel 12 miles upstream in 6 hours. Find the speed of the boat in still water and the speed of the current.
Answer by ankor@dixie-net.com(22740)   (Show Source):
You can put this solution on YOUR website! A boat can travel 20 miles downstream in 2 hours.
The same boat can travel 12 miles upstream in 6 hours.
Find the speed of the boat in still water and the speed of the current.
:
Let s = boat speed in still water
Let c = current speed
then
(s+c) = effective speed downstream
and
(s-c) = effective speed upstream
:
Write a distance equation for each way, dist = time * speed
2(s+c) = 20
6(s-c) = 12
simplify, divide the 1st equation by 2, divide the 2nd equation by 6
s + c = 10
s - c = 2
------------Adding eliminates c, find s
2s + 0 = 12
s = 12/2
s = 6 mph is the speed in still water
then
6 + c = 10
c = 4 mph is the current
;
:
Check solution in the original 1st equation
2(6+4) = 20
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