Question

The speed of a boat in still Water is 11km/h. It can go 12km upstream and return downstream to the original point in 2hrs 45mins. Find the speed of the stream.

Answer 1

Let the speed of stream be x

Speed of boat in still water = 11
Speed of boat upstream = 11-x
Speed of boat downstream = 11+x

Distance = 12
Distance/speed = time

12/(11-x) + 12/(11+x) = 2 hours 45min
12*(22/(121-x^2) = 11/4
x^2 = 25
x = 5
Speed of stream = 5km/hr