Question 542183: A river has two bridges spanning it that are exactly one mile from each other. While practicing for a boat race, a competitor went upstream. He rowed at a constant rate, and, in doing so, passed under the two bridges. Just underneath the second bridge his cap fell into the water. A further tem minutes passed before he realized that he had lost it. He then turned around and began rowing, still at the same constant rate, in the direction from which he had come. He finally caught up with the cap under the first bridge.
How fast does the river flow?
Answer by ankor@dixie-net.com(22740)   (Show Source):
You can put this solution on YOUR website! A river has two bridges spanning it that are exactly one mile from each other. While practicing for a boat race, a competitor went upstream.
He rowed at a constant rate, and, in doing so, passed under the two bridges.
Just underneath the second bridge his cap fell into the water.
A further ten minutes passed before he realized that he had lost it.
He then turned around and began rowing, still at the same constant rate, in the direction from which he had come.
He finally caught up with the cap under the first bridge.
How fast does the river flow?
:
The boat and the hat are in the same frame of reference, unaffected by the current.
If the boat traveled 10 min away from the hat, it would require 10 min to return.
During this 20 min time the current carried the hat from the 2nd bridge, back to the 1st bridge, a distance of 1 mile
Another words the hat traveled 1 mi in 20 min. Therefore we can say:
the current = 3 mph
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