The speed of a boat in still water is 8 km/h, while it takes 2 hours for the boat to cover a distance of 20 km downstream. What is the speed (in km/h) of the stream?
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 i.e 2.
Speed of boat in still water = 8 km/h
Distance downstream = 20 km
Time = 2 hours
So, downstream speed = distance ÷ time = 20 ÷ 2 = 10 km/h
Downstream speed = boat speed + stream speed
So, 10 = 8 + stream speed
Stream speed = 10 − 8 = 2 km/h