A man can swim in still water at 8 km/hr. If the river is flowing at 2km/hr he takes 80 minutes to reach a place and return back, how far is the place?

July 28, 2023

Question	A man can swim in still water at 8 km/hr. If the river is flowing at 2km/hr he takes 80 minutes to reach a place and return back, how far is the place?
Type	multiple_choice
Option	4 km	incorrect
Option	3 km	incorrect
Option	4.5 km	incorrect
Option	5 km	correct

Solution :

Let the place is X km far.

Speed downstream = 8+2=10 km/hr

Speed upstream = 8 – 2 = 6 km/hr

Time = Distance / Speed

x/6 + x/10 = 80/60

10x+ 6x/60 = 4/3

30X + 18X = 240

48X = 240

x = 240/80 = 5 km