A motor boat covers 48 km downstream in 2 hours and 42 km upstream in 3 hours. What is the speed of the boat in still water?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 19 km/hr
The speed in still water is half the sum of the downstream and upstream speeds, because the stream is added on one run and taken away on the other.
Downstream speed \(\displaystyle =\frac{48}{2}=24\) km/hr
Upstream speed \(\displaystyle =\frac{42}{3}=14\) km/hr
Speed in still water \(\displaystyle =\frac{24+14}{2}=19\) km/hr