Question 134374: A boat travels 60km upstream in 5 hours. The boat travles the same distance downstream in 3 hours. Whatis the rate of the boat in still water? what is the rate of the current?
okay I really tried, but i just can't get it...
s=d/T
s=60/5=12
60/3
12-10=2
Answer by ankor@dixie-net.com(22740)   (Show Source):
You can put this solution on YOUR website! A boat travels 60km upstream in 5 hours. The boat travels the same distance downstream in 3 hours. What is the rate of the boat in still water? what is the rate of the current?
:
Let s = speed of the boat in still water
Let c = speed of the current
Then
(s+c) = speed downstream
and
(s-c) = speed upstream
:
We can write two distance equations, one upstream, on downstream
Dist = time * speed
:
5(s-c) = 60
3(s+c) = 60
:
We can simplify both equations, divide the 1st one by 5, and the 2nd one by 3
s - c = 12
s + c = 20
------------adding equations eliminates c, find s
2s + 0 = 32
s = 32/2
s = 16 km/hr is speed in still water
:
Find c using the 2nd simplified equation
s + c = 20
16 +c = 20
c = 20 - 16
c = 4 km/hr is the speed of the current
:
Check solution in one of the original equations
5(16 - 4) = 60; confirms our solutions
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