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

Question 144580: 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?
Found 2 solutions by josmiceli, shahid:
Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
Let = speed of the boat in still water
The current = mi/hr
In words:
(distance traveled upriver)/(rate going upriver)
+ (distance traveled downriver)/(rate going downriver) = 9 hrs

multiply both sides by

divide both sides by

solve using quadratic fornula

mi/hr
If you plug this back into the original equation, it checks out
Answer by shahid(44) (Show Source): You can put this solution on YOUR website!
let x mph be the speed of the boat in still water then
(x+3)mph will be the speed of boat downstream
(x-3)mph will be its speed in upstream
now time taken by baot upstream t1=60/(x-3) and time taken by boat in downnstream t2=60/(x+3)
t1+t2=9
60/(x-3)+60/(x+3)=9
60{1/(x-3)+1/(x+3)}=9
x+3+x-3/x^2-9=9/60 taking LCM and dividing by 60
2x/x^2-9=3/20
20(2x)=3(x^2-9)
40x=3x^2-18
3x^2-40x-18=0 solve this equation to get your answer
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