SOLUTION: The speed of a stream is 3 mph. A boat travels 5 miles upstream in the same time it takes to travel 11 miles downstream. What is the speed of the boat in still water?
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Question 168443: The speed of a stream is 3 mph. A boat travels 5 miles upstream in the same time it takes to travel 11 miles downstream. What is the speed of the boat in still water? Answer by nerdybill(7384) (Show Source):
You can put this solution on YOUR website! The speed of a stream is 3 mph. A boat travels 5 miles upstream in the same time it takes to travel 11 miles downstream. What is the speed of the boat in still water?
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You will need to apply the "distance formula":
d = rt
where
d is distance
r is rate or speed
t is time
.
Since this problem is talking about "time" solve the equation for 't':
d =rt
d/r = t
.
Let x = speed of boat in still water
5/(x-3) = 11/(x+3)
Multiplying both sides by (x+3)(x-3):
5(x+3) = 11(x-3)
5x+15 = 11x-33
15 = 6x-33
48 = 6x
8 mph = x (speed of boat in still water)
