Question

The speed of the boat in still water is 11 km per hour it can go 12 km upstream and return downstream to the same spot in 2 hours 45 minutes find the speed of the stream

Answer 1

Speed of the boat in still water = 11 km/hr

Let the speed of stream = x km/hr

speed upstream = (11-x) km/hr

speed of downstream = (11+x) km/hr

According to the given condition  

{12/(11+x)}+{12/(11-x)} = 11/4

Solve  

Speed of the stream = 5 km/hr