Problema Solution
A paddle boat can move at the speed of 12 km/h in still water. The boat is paddled 8 km downstream in a river in the same time it takes it to go 4 km upstream. What is the speed of the water?
Answer provided by our tutors
Let
x = the speed of the water
v = 12 km/h the speed of the paddle boat in still water
The speed upstream: v - x = 12 - x
The speed downstream: v + x = 12 + x
Since speed = distance/time => time = distance / speed
The boat is paddled 8 km downstream in a river in the same time it takes to go 4 km upstream or
The time going 8 km downstream = The time going 4 km upstream
8/(12 + x) = 4/(12 - x)
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x = 4 km/h
The speed of the water is 4 km/h.