A motorboat travels 16 km in 2 hours against the flow of river and travels next 8 km along the flow of the river in 20 minutes. How long will it take motorboat to travel 48 km in still water?

July 28, 2023

Question	A motorboat travels 16 km in 2 hours against the flow of river and travels next 8 km along the flow of the river in 20 minutes. How long will it take motorboat to travel 48 km in still water?
Type	multiple_choice
Option	2.5 hours	incorrect
Option	3 hours	correct
Option	3.5 hours	incorrect
Option	4 hours	incorrect

Solution :

Speed = Distance / Time

Speed upstream = 19/2 = 8 km/hr

Speed downstream = 8/20/60 = 480/20 = 24 km/hr

∴ Speed in still water = = 1/2 (speed downstream +speed upstream)

= 1/2 ( 24 + 8) = 16 km/hr

Required time = Distance/ Speed still water

= 48/16 = 3 hour