SOLUTION: A boat travels 45 kms. upstream and then returns to the dock traveling 45 kilometers downstream. The speed of the boat in still water is 12 km/hr. The total time for the trip is 8
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Question 939724: A boat travels 45 kms. upstream and then returns to the dock traveling 45 kilometers downstream. The speed of the boat in still water is 12 km/hr. The total time for the trip is 8 hours. Find the speed of the current.
I got the answer to be the current = 3 km/hr. Is this correct?
Thank you! Answer by lwsshak3(11628) (Show Source):
You can put this solution on YOUR website! A boat travels 45 kms. upstream and then returns to the dock traveling 45 kilometers downstream. The speed of the boat in still water is 12 km/hr. The total time for the trip is 8 hours. Find the speed of the current.
***
let c=speed of current
12+c=speed of boat downstream
12-c=speed of boat upstream
Travel time=distance/speed
..
lcd:(12-c)(12+c)
45(12-c)+45(12+c)=8(12-c)(12+c)
540-45c+540+45c=8(12^2-c^2)
1080=8(144-c^2)
1080=1152-8c^2
8c^2=72
c^2=9
c=3
speed of current=3 km/hr
congratulations! You got it right.
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