SOLUTION: In testing the rate at which a polluted stream flows, a boat that travels at 5.5 km/h in still water took 5.0 h to go downstream between two points, and it took 8.0 h to go upstrea

Algebra ->  Equations -> SOLUTION: In testing the rate at which a polluted stream flows, a boat that travels at 5.5 km/h in still water took 5.0 h to go downstream between two points, and it took 8.0 h to go upstrea      Log On


   

Question 159813: In testing the rate at which a polluted stream flows, a boat that travels at 5.5 km/h in still water took 5.0 h to go downstream between two points, and it took 8.0 h to go upstream between the same two points. What is the rate of flow of the stream ?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
A boat that travels at 5.5 km/h in still water, took 5.0 h to go downstream
between two points, and it took 8.0 h to go upstream between the same two
points. What is the rate of flow of the stream ?
:
Let x = rate of the stream
Then
(5.5+x) = boat speed downstream
and
(5.5-x) = boat speed upstream
:
The distance for each trip is the same; write a dist equation; dist = time * speed
:
Dist down = dist up
5(5.5+x) = 8(5.5-x)
;
27.5 + 5x = 44 - 8x
:
5x + 8x = 44 - 27.5
:
13x = 16.5
x = 16.5%2F13
x = 1.27 km/hr is the rate of the stream
:
;
Confirm solution by finding the dist of each trip, should be equal
Speed upstream: 5.5-1.27 = 4.23
Speed downstream: 5.5+1.27 = 6.77
5(6.77) = 33.85 km
8(4.23) = 33.84 km; close enough
:
:
That wasn't so hard, was it? Any questions?