A paddle boat can move at a speed of 10 km/h in still water. The boat is paddled 6km downstream in a river in the same time it takes to go 3km upstream. What is the speed of the river?

Question

kira_yamato · Answer

Is the speed of the boat constant at 10km/h?

anonymous · Answer

That is all the info they give me.

anonymous · Answer

What do you mean @Chlorophyll?

anonymous · Answer

Downstream: ( 10 + r ) t = 6 km
Upstream:      ( 10 - r  ) t = 3 km

anonymous · Answer

Hint: equate them
( 10 + r ) / 6  =  ( 10 -r ) /3

anonymous · Answer

$$\frac{ 6 }{ 10+x }=\frac{ 3 }{ 10-x }$$

anonymous · Answer

Right I got that but for some reason I am still not coming up with an answer that looks correct. I got 10/3

anonymous · Answer

Well that's what I got was x=10/3

anonymous · Answer

Well the computer accepted that... I don't know what I was doing wrong... I kept just getting 10.

anonymous · Answer

Thank you!