SOLUTION: A boat travels 30 miles upstream in three hours. It makes the return trip in one and a half hours. What is the speed of the boat in still water?

Question 883918: A boat travels 30 miles upstream in three hours. It makes the return trip in one and a half hours. What is the speed of the boat in still water?
Found 2 solutions by Alan3354, josmiceli:
Answer by Alan3354(69443) (Show Source): You can put this solution on YOUR website!
Use d = r*t, r = d/t to find the speed up and downstream.
The boat's speed is the average of the 2.

Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
Let = the speed of the boat in still water
Let = the speed of the current
------------------
Going upstream:
(1)
Going downstream:
(2)
-----------------------
(1)
(2)
-----------------------
(1)
(2)
-----------------------
Multiply both sides of (1) by
and add the equations
(1)
(2)
-----------------------

------------
The speed of the boat in still water is 15 mi/hr
check:
(1)
(1)
(1)
and
(2)
(2)
(2)
(2)
OK

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