Question 940879: riley can paddle 30 miles downstream in 3 hours. upstream takes one hour more to go 6 miles less. Find the rate of the current.
Answer by ankor@dixie-net.com(22740)   (Show Source):
You can put this solution on YOUR website! Riley can paddle 30 miles downstream in 3 hours.
upstream takes one hour more to go 6 miles less.
Find the rate of the current.
:
let s = his paddling speed in still water
let c = the rate of the current
then
(s+c) = his effective speed downstream
and
(s-c) = his effective speed upstream
:
Write a distance equation for each way; dist = time * speed
3(s+c) = 30
4(s-c) = 24; (one hr longer and 6 mi less)
:
We can simplify both these equations, divide the 1st one by 3, the 2nd one by 4
s + c = 10
s - c = 6
----------Adding eliminates c, find s
2s = 16
s = 16/2
s = 8 mph
find the current using the equation s + c = 10
8 + c = 10
c = 10 - 8
c = 2 mph is the current
:
:
you can confirm this by putting these values in the original equations
|
|
|
