capegemini - the rate of current is 5kmhr and the speed of boat in still water is 19kmhr the ratio between the distance travelled downstream in 15 minutes to the distance travelled upstream in 30 minutes is - skillgun

If the speed of boat in still water is u km/hr and the speed of the stream is v km/hr, then:
Speed downstream = (u + v) km/hr.
Speed upstream = (u - v) km/hr.
Given that the speed of boat in still water is 19 km/hr and the rate of current is 5 km/hr.
Downstream speed = (19 + 5) km/hr = 24km/hr
Distance travelled downstream in 15 minutes with a speed of 24km/hr = 24 x (15/60) = 6 km
Upstream speed = (19 - 5) km/hr = 14km/hr
Distance travelled upstream in 30 minutes with a speed of 14km/hr = 14 x(30/60) = 7 km
Then the required ratio = 6:7 = 3 : 3.5
Hence the answer is 3 : 3.5