SOLUTION: A boat travels 9 km upstream and 9 km back. The time for the round trip is 3 hrs. The speed of the stream is 5 ​km/hr. What is the speed of the boat in still​ water?

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Question 1116608: A boat travels 9 km upstream and 9 km back. The time for the round trip is 3 hrs. The speed of the stream is 5 ​km/hr. What is the speed of the boat in still​ water?
Answer by josgarithmetic(39620)   (Show Source): You can put this solution on YOUR website!
r, boat speed if no stream current 
           SPEED       TIME             DISTANCE

UP          r-5                   9

DOWN        r+5                   9

TOTAL                  3


-






--
discriminant




8.8 km/hour
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