SOLUTION: The Hudson River flows at a rate of 3 miles per hour. A patrol boat travels 60 miles upriver, and returns in a total time of 9 hours. What is the speed of the boat in still water

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons  -> Quadratic Equation Lesson -> SOLUTION: The Hudson River flows at a rate of 3 miles per hour. A patrol boat travels 60 miles upriver, and returns in a total time of 9 hours. What is the speed of the boat in still water      Log On


   

Question 26884: The Hudson River flows at a rate of 3 miles per hour. A patrol boat travels 60 miles upriver, and returns in a total time of 9 hours. What is the speed of the boat in still water?
Can you please help me?! This is due soon and I've been racking my brain at it and still can't get it.....
Answer by Paul(988) About Me  (Show Source):
You can put this solution on YOUR website!
Since its total time of 9 hours you knwo that its first speed + the second.
60%2F%28x%2B3%29-60%2F%28x-3%29=9
60[(x+3)+(x-3)]=9[(x+3)(x-3)]
60%282x%29=9%28x%5E2-9%29
120x=9x%5E2-81
9x%5E2-120x-81=0%2Cx
Use the quadratic formula and simplfy you get
x=13.9777...
Round it out
Hence, the speed of the boat is 14mph in still water.
Paul.