Boat and streams

Aptitude question based on boat and streams

Mainly 4 Terms are commonly used in boat and streams problems are :

1. Speed of boat
2. Speed of stream
3. Upstream speed - In water, direction along the stream / flow of water
4.Downstream speed - In water , direction against the stream / flow of water

If speed of boat is X and speed of stream is Y.

Downstream speed = X + Y
Upstream speed = X - Y

If Downstream speed is "a" and Upstream speed is "b".

Speed of the boat in still water = (a+b)/2
Speed of stream = (a-b)/2

If a boat travel a particular distance 'd' in upstream and downstream within time 't'.

Time = d/(a+b)+d/(a-b)

Questions

1. A boat can travel with a speed of 22 km/hr in still water. If the speed of the stream is 6 km/hr, find the time taken by the boat to go 112 km downstream.

Downstream speed = 22 + 6  km/hr = 28 km/hr.

Time taken to travel 112 km downstream  = 112/28 = 4

Answer is 4 hour