A paddle boat can move at a speed of 6km/h in still water. The boat is paddled 16 km downstream in a river in the same time it takes to go 8 km upstream. What is the speed of the river?
Let speed of river be S
Time it takes to travel DOWNSTREAM:
Time it takes to travel UPSTREAM:
We then get the following TIME equation:
8(6 + S) = 16(6 - S) ----- Cross-multiplying
6 + S = 2(6 - S) --------- Dividing each side by GCF, 8
6 + S = 12 - 2S
S + 2S = 12 - 6
3S = 6
S, or speed of river =
It's that easy....nothing complex!!