SOLUTION: The current of a river is 4 miles per hour. A boat travels to a point 30 miles upstream and back in 4 hours. What is the speed of the boat in still water?

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Question 810058: The current of a river is 4 miles per hour. A boat travels to a point 30 miles upstream and back in 4 hours. What is the speed of the boat in still water?

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Since the current reduces the boat's speed in
one direction and increases the speed by the
same amount in the opposite direction,
you can disregard the effect of the current
+d+=+r%2At+
+30+%2B+30+=+r%2A4+
+60+=+4r+
+r+=+15+
The speed of the boat in still water is 15 mi/hr