The speed of a motor boat in still water is 20 km/hr. It covers 78 km downstream in 3 hours. What is its speed when it goes upstream?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 14 km/hr
The downstream run gives the stream’s speed; taking it away from the boat’s speed gives the upstream speed.
Downstream speed \(\displaystyle =\frac{78}{3}=26\) km/hr
Speed of the stream \(=26-20=6\) km/hr
Upstream speed \(=20-6=14\) km/hr