# SOLUTION: This is a strange problem our instructor gave us to solve. I cannot figure out how to do this particular probem. Can someone please help? Here it is. The Ohio River flows at a

Algebra ->  Algebra  -> Customizable Word Problem Solvers  -> Travel -> SOLUTION: This is a strange problem our instructor gave us to solve. I cannot figure out how to do this particular probem. Can someone please help? Here it is. The Ohio River flows at a       Log On

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 Click here to see ALL problems on Travel Word Problems Question 187033: This is a strange problem our instructor gave us to solve. I cannot figure out how to do this particular probem. Can someone please help? Here it is. The Ohio River flows at a rate of 5 miles per hour. A patrol boat travels 40 miles upriver and returns in a total of 6 hours. What is the speed of the boat in still water? I am so confused...Answer by ankor@dixie-net.com(15746)   (Show Source): You can put this solution on YOUR website! The Ohio River flows at a rate of 5 miles per hour. A patrol boat travels 40 miles upriver and returns in a total of 6 hours. What is the speed of the boat in still water? : Let s = boat speed in still water then (s+5) = boat speed down-stream and (s-5) = boat speed up-stream : Write a time equation; Time = ; Upstream time + downstream time = 6 hrs + = 6 : Multiply equation by (s-5)(s+5) and you have: 40(s+5) + 40(s-5) = 6(s+5)(s-5) : 40s + 200 + 40s - 200 = 6(s^2 - 25) : 80s = 6s^2 - 150 : 0 = 6s^2 - 80s - 150; a quadratic equation Simplify, divide by 2 3s^2 - 40s - 75 = 0 Factors to: (3s + 5) (s - 15) = 0 The positive solution is what we want s = 15 mph is the speed in still water ; ; Check solution in our original equation 40/20 = 2 hr 40/10 = 4 hr ; : Did this reduce the confusion somewhat? Any questions?