A man rows downstream at 20 km/hr and rows upstream at 15 km/hr. At what speed he can row in still water?

July 27, 2023

Question	A man rows downstream at 20 km/hr and rows upstream at 15 km/hr. At what speed he can row in still water?
Type	multiple_choice
Option	17.5 km/hr	correct
Option	18 km/hr	incorrect
Option	20.5 km/hr	incorrect
Option	22 km/hr	incorrect

Solution

Apply formula: Speed in still water 1/2

(speed downstream + speed upstream)

Speed downstream = 20 km/hr

Speed upstream = 15 km/hr

∴ Required speed = 1/2 (20 + 15) km/hr

= 1/2 * 35 = 17.5 km/hr