1954 AHSME Problems/Problem 36
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Problem 36
A boat has a speed of mph in still water. In a stream that has a current of mph it travels a certain distance downstream and returns. The ratio of the average speed for the round trip to the speed in still water is:
Solution 1
WLOG, let the distance the boat travel be mile. Then the boat takes minutes, to travel down a mile, then to travel back up the river, the boat travels miles per hour, taking minutes to travel up the river. This gives an average speed of which as a ratio to is