Problema Solution
A boat travels 3km upstream and 3km back. The time for the round trip is 5hrs. The speed of the stream is 5 km/hr. What is the speed of the boat in still water?
Answer provided by our tutors
Boat speed x
current speed 5
against current x- 5 kph
with current x+ 5 kph
Distance= 3 km
Time against + time with = 5 hours
t=d/r
3 /( x + 5 ) + 3 /(x - 5 ) = 5
6x/(x^2 - 25) = 5 ==> 6x = 5(x^2 - 25) ==> 5x^2 -6x-125 = 0
x = (1/5)(3+sqrt(634))
x = 5.636