Problema Solution
The Congo River flows at a rate of 15 km/hr for the length of a popular scenic route. In order for a cruiser to travel 80 km upriver and then return in a total of 6 hr, how fast must the boat be able to travel in still water?
Answer provided by our tutors
let
c = 15 km/hr the current of the river
v = the rate of the boat in still water, v>0
traveling upriver the rate of the boat is: v - c = v - 15
traveling downstream the rate of the boat is: v + c = v + 15
since speed = distance/time => time = distance/speed
80/(v - 15) + 80/(v + 15) = 6 multiply both sides by (v - 15)(v + 15)
80(v + 15) + 80(v - 15) = 6(v - 15)(v + 15)
by solving we find
v = 33.04 km/hr
click here to see the step by step solution of the equation
the boat must be able to travel with 33.04 km/hr in still water.