SOLUTION: Please help! I really need to learn how to do travel word problems and they confuse me so much. The speed of a river's current is 4 miles per hour. You travel 2 miles with the

Question 571707: Please help! I really need to learn how to do travel word problems and they confuse me so much.
The speed of a river's current is 4 miles per hour. You travel 2 miles with the current and then return to where you started in a total time of 1.25 hours. What is your speed in the still water in miles per hour?
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
The speed of a river's current is 4 miles per hour.
You travel 2 miles with the current and then return to where you started in a total time of 1.25 hours.
What is your speed in the still water in miles per hour?
:
let s = the speed of your boat in still water
then
(s-4) = your effective speed up-stream
and
(s+4) = your effective speed down-stream
:
Write a time equation; time = dist/speed
:
Time upstr + time downstr = 1.25 hrs
+ = 1.25
Multiply by (s-4)(s+4)
(s+4)*s-4) + (s+4)(s-4* = 1.25(s+4)(s-4)
Cancel the denominators, and you have
2(s+4) + 2(s-4) = 1.25(s^2-16)
:
2s + 8 + 2s - 8 = 1.25s^2 - 20
Combine to form a quadratic equation
0 = 1.25s^2 - 4s - 20
You have to use the quadratic equation to find s
only on solution will make sense, I got
5.91 mph is his approx speed in still water
RELATED QUESTIONS
( word prob.) Abby rows 10 km upstream and 10 km back in a total of 3 hr. the speed of... (answered by jim_thompson5910)

Please help me solve this complex number. The problems that contain "i"'s really confuse... (answered by edjones)

Hello, Please help with this word problem and show steps on how you recieved... (answered by checkley71)

please help me solve this equation. i am just starting to learn and problems like these... (answered by stanbon)

I really need to know how to solve travel and distance problems (word problems). I do... (answered by htmentor)

I don't have any idea how to do these word problems. I've been trying but I just don't... (answered by KnightOwlTutor)

I have a test that is coming up this Sunday and I need to know how to solve these type of (answered by ewatrrr)

Two airplanes leave simultaneously from an airport. One flies due south; the other flies (answered by nerdybill)

Karen�s boat has a top speed of 10 miles per hour in still water. While traveling on a... (answered by josmiceli)