SOLUTION: The speed of the boat is 10km/h and the speed of the river is 2km/h. Travelers take the boat and want to be back to where they started in 10hours. How far should they go, before tu

Question 948252: The speed of the boat is 10km/h and the speed of the river is 2km/h. Travelers take the boat and want to be back to where they started in 10hours. How far should they go, before turning around
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
The speed of the boat is 10km/h and the speed of the river is 2km/h.
Travelers take the boat and want to be back to where they started in 10 hours.
How far should they go, before turning around
:
let d = the one-way distance, (the point where they return)
:
We know from the information given that:
10 - 2 = 8 km/h the effective speed upstream
and
10 + 2 = 12 km/h the effective speed downstream
;
Write a time equation, time = dist/speed
:
time up + time back = 10 hrs
+ = 10
multiply equation by 24
24* + 24* = 24*10
cancel the denominators
3d + 2d = 240
5d = 240
d = 240/5
d = 48 km to the point where they should turn back
:
:
Confirm this by finding the actual time each way
48/8 = 6 hrs
48/12 = 4 hrs
-------------------
total time 10 hrs

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