word problem

Question

a paddle boat can move at a speed of 18km/h in still water. the boat is paddled 22 km downstream in a river in the same time it takes to go 11km upstream. what is the speed of the river ?

Answer 1

let t be the time

let x be the speed of the river

 

t(18 + x) = 22

 

t(18 - x) = 11

 

t = 22/(18 + x)

 

[22/(18 + x)](18 - x) = 11

 

396 - 22x = 198 + 11x

 

396 - 198 = 22x + 11x

 

198 = 33x

 

x = 6 km/hr