SOLUTION: The Hudson River flows at a rate of 5 miles per hour. A patrol boat travels 40 miles upriver and returns in a total time of 6 hours. What's the speed of the boat in still water?

Algebra.Com
Question 180565: The Hudson River flows at a rate of 5 miles per hour. A patrol boat travels 40 miles upriver and returns in a total time of 6 hours. What's the speed of the boat in still water?
Answer by HyperBrain(694)   (Show Source): You can put this solution on YOUR website!
Let r=rate of boat in still water
Then r-5=rate of boat upstream

r+5=rate of boat downstream

40(r+5)+40(r-5)=6(r2-25)
40(2r)=80r=6r2-150
6r2-80r-150=0
3r2-40r-75=0
(r-15)(3r+5)=0
r-15=0
r=15
3r+5=0
r=-5/3>>Not valid since the rate of the boat must be positive.
Therefore, the boat travels 15 mi/hr in still water.
Power up,
HyperBrain!
View my Wordpress here
Are you plastic? Click here

RELATED QUESTIONS

The Hudson River flows at a rate of 5 miles per hour. A patrol boat travels 40 miles... (answered by MissionPossible)
4. The Hudson River flows at a rate of 5 miles per hour. A patrol boat travels 40 miles... (answered by solver91311)
The Hudson River flows at a rate of 5 miles per hour. A patrol boat travels 40 miles... (answered by Alan3354)
4. The Hudson River flows at a rate of 5 miles per hour. A patrol boat travels 40 miles... (answered by solver91311)
4. The Hudson River flows at a rate of 5 miles per hour. A patrol boat travels 40 miles... (answered by ptaylor)
4. The Hudson River flows at a rate of 5 miles per hour. A patrol boat travels 40 miles... (answered by solver91311)
The Hudson River flows at a rate of 5 miles per hour. a patrol boat travels 40 miles... (answered by stanbon)
The Hudson River flows at a rate of 5 miles per hour. A patrol boat travels 40 miles... (answered by solver91311)
4. The Hudson River flows at a rate of 5 miles per hour. A patrol boat travels 40 miles... (answered by jim_thompson5910)