Problema Solution
The current in a stream is 4 km/h. A boat travels 24 km upstream and 24 km downstream in a total time of 8 hours. What is the speed of the boat in still water?
Answer provided by our tutors
let speed of boat = x
speed upstream = x - 4
speed downstream = x + 4
solving 24/(x+4) + 24/(x -4) = 8
(x-4 + x +4)/(x^2 -16)= 1/3
6x = x^2 - 16
x^2 - 6x - 16=0
(x-8)(x+2)=0
x = 8, -2
so we get x = 8
speed of boat = 8 kmper hour