SOLUTION: I am a librarian. A patron needs a solution to this problem:
The speed of a boat in still waters is 10 km/h
The boat travels 12 km upstream and 28 km downstream in a total of 4
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-> SOLUTION: I am a librarian. A patron needs a solution to this problem:
The speed of a boat in still waters is 10 km/h
The boat travels 12 km upstream and 28 km downstream in a total of 4
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Question 736018: I am a librarian. A patron needs a solution to this problem:
The speed of a boat in still waters is 10 km/h
The boat travels 12 km upstream and 28 km downstream in a total of 4 hours.
What is the speed of the stream?
Thanks Answer by mananth(16946) (Show Source):
You can put this solution on YOUR website! let speed of current be c kph
upstream speed = 10-c
upstream distance = 12
down stream speed = 10+c
down stream distance = 28 km
upstream time + downstream time = 4
t=d/r
12/(10-c) + 28/(10+c)= 4
multiply the equation by (10+c)(10-c)
12(10+c)+28(10-c)=4(10+c)(10-c)
120+12c+280-28c=4(100-c^2)
400-16c=400-4c^2
re arrange
4c^2=16c
/4c
c=4
