SOLUTION: Bob travels 4 miles upstream. In the same time, he could have traveled 7 miles downstream. If the speed of the current is 3 mph, find the speed of the boat in still water.

Algebra ->  Customizable Word Problem Solvers  -> Travel -> SOLUTION: Bob travels 4 miles upstream. In the same time, he could have traveled 7 miles downstream. If the speed of the current is 3 mph, find the speed of the boat in still water.       Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


    

Question 675455: Bob travels 4 miles upstream. In the same time, he could have traveled 7 miles downstream. If the speed of the current is 3 mph, find the speed of the boat in still water.

Answer by lwsshak3(11628) About Me  (Show Source):
You can put this solution on YOUR website!
Bob travels 4 miles upstream. In the same time, he could have traveled 7 miles downstream. If the speed of the current is 3 mph, find the speed of the boat in still water.
**
let x=speed of the boat in still water
x-3=speed upstream
x+3=speed downstream
travel time=distance/speed (same for upstream and downstream travel)
4/(x-3)=7/(x+3)
4x+12=7x-21
3x=33
x=11
speed of the boat in still water=11 mph